How much does it cost to install a rainwater collection system?

Reviewed by Cristina Miguelez remodeling expert. Written by Fixr.com.

A rainwater collection system is a way to capture rainwater to save and distribute later. They can be simple or complex, but either way are a great way to save on your water bill and conserve water over the long term.

If you live in an area that experiences drought or if you find yourself frequently watering your lawn or garden, having a rainwater storage and distribution system can help offset relying on the municipal water supply.

The cost to install a rainwater collection system varies based on the type of system, materials, and needed labor. The national average cost ranges from $1,000 to $3,500, with many homeowners paying about $2,500 for a dry system with a 5,000 gallon polyethylene storage tank installed. For a 55 rain barrel with a spigot, the costs can be as low as $150. On the other end, prices can rise to $15,000 for a 5,000-gallon steel tank with a wet system, irrigation, excavation, and a sprinkler.

Rainwater Harvesting System Cost

Rainwater Collection System Costs by Method

There are two main methods for harvesting rainwater: rooftop rainwater harvesting and surface runoff harvesting. These methods work differently, but both involve collecting and storing rainwater for reuse, rather than simply letting it run off and drain away.

Rooftop Rainwater Harvesting

Rooftop rainwater harvesting is much cheaper than surface runoff harvesting and costs between $1,000 and $5,000 on average. This method focuses on collecting rainwater directly from the roof. It uses the roof as a catchment device, letting water land on the roof panes, flow into the gutters, and then be redirected into a tank. At a minimum, this system requires a collection area, a conveyance system, and somewhere for the water to be stored. In addition to being less costly, this method is also environmentally friendly.

Surface Runoff Harvesting

Surface runoff harvesting focuses on collecting runoff rainwater but involves a lot of labor and digging and has costs that range from $8,000 to $15,000. This means letting the rain fall on the ground and then having it flow into a tank, which is usually situated below the ground. Unlike with a rooftop system, surface runoffs make use of the ground itself as the collection area for the rainwater. It flows along the ground and down into grates, where it enters underground pipes and flows into a tank.

In-ground surface runoff systems must be located at least 10 feet away from any watertight sewer line and 50 feet away from any non-watertight sewer line to avoid contamination. If you cannot work within those limits, you may have to stick with an above-ground system. A surface runoff system can have one grate or several, depending on your specific needs.

Rainwater Collection System Cost by Type

There are different types of rainwater collection systems, varying in capacity, function, and price. You can get very simple rainwater collection systems like barrels that sit out in the open and collect rainwater that runs off the roof, as well as much more complicated systems involving pipes flowing from the roof down underground into below-surface tanks. The most common rainwater collection methods make use of the rooftop harvesting method, and the table below shows three common types, along with a price range.

Rain Barrel

Rain barrels cost about $120 to $160 and are the simplest method for collecting rainwater. Home rain barrels range from 40 to 120 gallons. The most common size is 55 gallons. This rainwater collection method has no installation price since it consists of nothing more than placing a rain barrel under a gutter. A rain barrel connects to a gutter downspout and usually has a cover and a spigot at the base for distribution. Raising the barrel above ground level will allow gravity to push water out. Some people may worry that having big barrels sitting alongside their home could look unsightly, but these days, there are plenty of decorative rain barrels available. Some homeowners use them as outdoor furniture, painting the exterior and growing plants on the top to enhance the look of their rainwater collection system.

Dry System of Rainwater Harvesting

Dry rainwater collection systems cost between $1,000 and $5,000. A ‘dry’ system is essentially a larger version of a rain barrel. A dry system uses a large storage tank that is placed close to the house for water to flow from the gutter pipes directly into the storage tank. This is called a dry system because the collection pipe is “dry” in between rainfalls, as the water flows straight into the tank. The largest portion of the cost of a dry system is the storage tank, which varies based on capacity and storage material. A 5,000-gallon polyethylene tank costs about $2,000 to $4,000.

The main benefit of a dry system is how simple it is. The pipes run directly from the gutters to the tank, emptying themselves in the process, with minimal maintenance required. On the downside, they involve the use of barrels or tanks placed above the ground very close to your home, which may be an issue for some homeowners.

Wet System of Rainwater Harvesting

A wet system is much more complex than a dry system. It costs about $8,000 to $15,000 for an average tank that holds about 5,000 gallons. The price may increase if you choose a larger tank. With this type of system, the pipes are located underground, and all gutters eventually feed into this system. The pipes fill with water until there is enough to spill over into the storage tank. These systems are known as wet systems because the pipes remain filled with water at all times unless you empty them somehow. The big benefit of a wet system is that the pipes are hidden away, so they will not interfere with the aesthetics of your property. On the downside, the pipes can be vulnerable to issues like bug infestations and debris accumulation, so it requires good filters and regular maintenance.

Due to the need for underground piping, it costs significantly more than a dry system or rain barrel. The excavation cost runs $440 to $760 for three hours of access to the excavator and an operator. You will also need to factor in the price of the tank you choose.

However, prices vary based on any extra items you would like to add. For instance, if you want to install a 5,000-gallon ‘wet’ tank with a sprinkler system, you’ll pay $4,000 to $7,000 for the irrigation and sprinkler installation. Another addition you might want is a water treatment system, which is about $2,500 to $3,000. Neither of these items are required for a basic rainwater gathering system. The water treatment system isn’t needed if your water will be used for irrigation. Sprinkler systems are also not mandatory, but are often installed at the same time as a wet system.

Rainwater Tank Price by Material

The tank makes up the largest portion of a rainwater recycling system cost in many cases. They are required for use with dry and wet rainwater harvesting systems. The only difference is one is above ground, and one is below ground. Tanks vary in size and range from about 600 to 50,000 gallons in capacity. Small homes may need only a 2,500 gallon tank, while large properties with a lot of landscaping may require a 10,000 gallon tank. An average tank size of 5,000 gallons is reasonable for a large number of homeowners, which is reflected in the table and information below.

Polyethylene Tank

Homeowners can expect to pay $2,000 to $4,000 for a polyethylene rainwater tank. This is one of the most common options for water harvesting across the United States. There are several reasons to consider choosing this material for your tank. It is affordable compared to many other materials. It also comes in a variety of colors and sizes and is lightweight compared to steel or concrete tanks. These tanks are made of flexible plastic and come in opaque or translucent versions. Solid opaque tanks are considered the best option since algae are less likely to grow inside. They can only be used above ground or as a partially buried option.

Fiberglass Tank

When choosing a fiberglass tank, you pay $2,000 to $5,000. One of the perks of a fiberglass tank is that it is sturdy and durable enough to be installed above or below the ground. This tank is lightweight like polyethylene but rigid and fairly simple to repair when needed. However, any parts that have been cut will be sharp and fine, so caution should be used when touching those areas of the tank.

Steel Rainwater Tanks

A steel tank is a bit pricier at $3,000 to $6,000 but offers many exceptional benefits. These tanks are easy to access, very durable, and have an aesthetic that many appreciate. A steel tank ranges in size from a few hundreds of gallons to many thousands of gallons, so they work for most anyone’s needs. In most cases, a vinyl bladder is inside the steel tank and is the vessel that holds the water. These tanks are often assembled at your home due to their large size. Steel can corrode when buried, so these tanks are typically used above ground.

Concrete Rainwater Tanks

The final option is a concrete water tank, ranging from $3,000 to $6,000. The main benefits of concrete are its heaviness, durability, and strength. This type of tank can be used above ground or underground for versatility. They come in two forms, including ferro-concrete and monolithic-pour concrete. The former is a new style where a mixture of concrete is applied to a metal frame. Monolithic-pour means the tanks are prefabricated or poured in place before assembly. Concrete also has the advantage of increasing the pH of water.

Labor Costs to Install a Rainwater Harvesting System

The tank seller may provide installation services, but certain landscapers may also be able to install these collection systems. An average project involves preparing the tank area, connecting the tank to the downspout(s), and connecting the tank to a pump and any pipes or exit points. Landscapers charge on average $50 to $100 per hour. Installation time will vary based on the size and scope of your project. A sprinkler system and irrigation for a wet system will take 24-36 labor hours and will cost about $120 to $1,600 just for labor.

A dry system needs to be placed close to the house, but a wet system can be installed farther away from the building. Rain barrels should be directly underneath a downspout. Screens are not required, but they prevent debris and leaves from getting into your rainwater.

Rainwater Tank Installation System

These tanks vary in size, and the installation cost varies. It largely depends on the materials used to make the tank and the size of the tank itself. The simplest tank installation might cost around $250. However, a more intricate installation could reach a price of $1,300 or more. Depending on the type of tank you choose and the company you get it from, they may handle the installation for you. However, it is a good idea to get quotes from several providers. The best person to handle the job is a professional plumber. The cost ranges from $75 to $130 per hour of work.

A wet system, typically used for large homes farther away from the catchment location, would also need excavation to bury the storage tank. You would need to pay for excavation equipment rental and an operator, and the project would probably take about 3 hours and cost $440 to $760. This is not required for an above ground tank, making the costs lower.

Downspouts and Gutters for Rainwater Collection

Some homeowners need to install downspouts and gutters to create a harvesting system. In other cases, these components may be damaged or old and require replacement. In either of these cases, a professional can help with the process. If the downspouts are being replaced or installed, the price ranges from $300 to $600. When you need gutters, a professional can install them for $900 to $5,000.

Piping for Rainwater Collections System

The cost of piping is another consideration for those who have wet rainwater harvesting systems or other systems quite a distance from the home. A plumber will install the correct pipes to go from the tank to the home at a rate of $75 to $130 an hour. When pipes need to be installed, the process is more involved. The configuration takes more money and work. Typically, three to four inch pipes will be installed underground. In addition, a ditch must be dug, and a diverter will need to be installed.

Components of Rainwater Harvesting System

Every rainwater collection system has certain essential components, including filtration, a conveyance system, water storage, and a collection area. The prices for these components vary, depending on the size, type, and scale of your system, but the table below provides general estimates.

Rainwater Filtration System

Filters vary in style and functionality but usually cost between $75 and $200. Filtration is not always necessary for a rainwater collection system, but if you plan on reusing the water around the home, it is essential to install a filter to rid it of bacteria and other undesirable elements. These filters should be cleaned daily after any rain falls. If the filter becomes clogged, it may not move into the storage tank, and the filter could start to overflow.

Conveyance System

For a conveyance system, the price varies from as low as $100 for simple systems to $1,500 or more for more complex systems. The conveyance system of any rainwater collection system consists of pipes and fittings. The number and length of pipes required depend on the size and type of system you install.

Water Storage

Since there are many kinds of water storage, the price range is broad, from $120 to $6,000. The water storage component is one of the most expensive parts of a rainwater collection system. This can be anything from a simple rain barrel placed beside your house to a vast underground tank with a huge capacity.

Collection Area

The average cost of the collection area ranges from $500 to $9,000. The collection area for a rooftop collection system is the roof and gutters, whereas the cost for a surface runoff system is the section of ground where you want the water to flow and enter the tank. The prices for these areas vary enormously, depending on the type of system, the topography of your property, and the size of your home.

Optional Components of a Rainwater Collection System

As well as the essential parts of a collection system, there are several optional parts to consider. These add-ons help improve your system in a variety of ways, from transporting the rainwater more efficiently to removing debris from the water as it enters the tank. The table below shows some optional components and their price ranges.

Gutter Mesh

Expect to pay about $0.80 to $1.25 per linear foot of gutter mesh. Gutter mesh can be installed onto your home’s gutters. It acts as a filter for large items like leaves and other debris, preventing them from flowing along with the rainwater and ending up inside your tank. The mesh is a physical barrier that maximizes the amount of rainwater that can be collected. It also protects from sediment that would damage the pumps past the tank.

Gutter Outlets

Gutter outlets cost around $5 to $10 each. Gutter outlets, sometimes referred to as downspout connectors, are used to channel the water from the gutter into the downspout. Downspouts are recommended for every 20 feet of gutter, and every downspout needs a gutter outlet. Gutter outlets increase water flow and the life of home gutters. They prevent pooling and snags while preventing gutter corrosion.

Downspout Screens

The average downspout screen costs around $10 to $50. Downspout screens are fitted at the tops of each downspout and also serve as filters to prevent bugs, leaves, and other debris from entering the pipes or flowing into the storage tank. They are essential for rainwater collection systems where the owner plans to use the water in the home for things like bathing. Some versions both filter the water and divert it to a location of the homeowner’s choice. In this case, a tank overflow pipe may not be a requirement.

Tank Screen

Tank screens are another layer of filtration to shield your collected rainwater from unwanted elements, and costs range from $10 to $50 each. Tank screens are fitted over the tank, at the lid, and filter out debris, leaves, bugs, and more. This accessory offers one of the best and easiest methods of keeping water clean without extra work. In addition to filtering out debris, it also prevents excess sunlight from reaching the water, leading to algae.

First Flush Diverter

A first flush diverter usually costs between $20 and $60. A first flush diverter is another essential add-on if you plan to use the rainwater in your home for bathing, drinking, or other uses. It is used to flush away the first layer of rainwater because it is usually quite dirty and filled with toxins and should not be used. In some areas, this device is required. Even in locations where it is not, it is a good option to ensure clean water.

Tank Gauge

Tank gauges range from $30 to $50. A tank gauge is another optional component you might consider if you plan on keeping a close eye on your collection system to ensure that it stays running smoothly. The gauge allows you to see the water level inside the tank at any time so that you know exactly how much water is in there. Tank gauges can be found in both analog and digital formats. Keeping an eye on the water level ensures you do not run out.

Top-Up System

A top-up system is used to automatically fill up the tank with water and usually costs about $100 to $200. This prevents the tank from dropping below a set level. If the tank starts to go dry, a valve can open to allow in well or municipal water. This ensures that you continue to have water access even if there has been no or little rain in your area over the last few days or weeks.

Pump

Pump prices range between $150 and $300. A pump is used to distribute the water through the pipes, pushing it along and making it easier to extract or divert to certain areas or into the home. This makes it much easier to reuse your water, either inside or outside. Some of the things to consider when choosing a pump are the electrical needs, pump style, installation location, head or pressure required, and the flow rate you desire. For instance, a garden hose might use around three gallons a minute, while a washing machine could use two gallons a minute.

Is It Against the Law to Collect Rainwater?

It depends on where you live. In most states, it’s legal to collect your own rainwater for watering lawns and gardens, but it may be against the law to collect rainwater for drinking. Check your local ordinances to be certain of the regulations in your area of the country. States will fall into one of three categories:

Some states allow water harvesting with restrictions, others make it legal without restrictions, and some states actively encourage the process. Below is where each state falls. However, checking on extra information is a good idea before you begin thinking about installing your own rainwater harvesting system:

The states that are least lenient and allow harvesting of rainwater but have restrictions include Arkansas, California, Colorado, Georgia, Idaho, Illinois, Louisiana, Nevada, North Carolina, Ohio, Oregon, Texas, and Utah. As an example of the laws in these states, Arkansas only allows rainwater to be used for potable purposes if the harvesting system was designed by a licensed professional engineer in the state with cross-connection safeguards and compliance with the Arkansas Plumbing Code.

The states where rainwater harvesting is legal include Alabama, Alaska, Arizona, Iowa, Kansas, Kentucky, Maine, Mississippi, New Jersey, Oklahoma, South Dakota, Tennessee, Vermont, Washington, West Virginia, Wisconsin, and Wyoming.

States that not only allow rainwater harvesting but encourage it among the residents include Connecticut, Delaware, Florida, Hawaii, Indiana, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Montana, Nebraska, New Hampshire, New Mexico, New York, North Dakota, Pennsylvania, Rhode Island, South Carolina, and Virginia.

One of the main reasons that these regulations are in place is based on overall water rights. The use of rainwater collectors could be considered to infringe on the rights of someone else “downstream” of your location. This legislation is often in place in areas with droughts or other water issues.

Benefits of Collecting Rainwater

There are many benefits to installing a rainwater collection system and collecting rainwater for your home, and these benefits apply to all kinds of systems. The first and most obvious benefit is that rainwater is free, so having a collection system lets you gather your own source of free water. It also does not contain any added chemicals or additives that may be found in municipal supplies, and this helps to make it much safer to use for landscaping and general gardening.

Collecting rainwater can save you money on your water bills too, as well as reducing the possibility of flooding if you live in a flood-prone area. Plus, with the right add-ons like filters and first flush systems, collected water can be used in your home for all kinds of things like bathing and even drinking. There are a couple of downsides, however, because these systems can be expensive and take up space around the home. Also, you can never predict when rain will fall.

How Do You Calculate Rainwater Tank Capacity?

To ensure you select a rainwater tank that is large enough for your needs, it is important to know the average rainfall in your area. Other factors that come into play are the size of your roof, how much water you usually use in the home, and whether this will be the only water source. The roof size is calculated in square feet and determines how much water you may be able to harvest. Take the square footage of the roof and multiply it by the average rainfall depth. Next, multiply the result by a 0.623 conversion factor. For example, one inch of rainfall on a roof of 2,000 square feet with the conversion equals about 1,250 gallons of water. Your tank should be able to hold that amount or more.

However, the average rainfall may not always be completely accurate. In most cases, the company that installs your rainwater collection system will provide you with a water meter before installing the system. In some cases, this is a complimentary product. In other cases, you might wish to purchase your own to be sure you get a system that is ideal for your situation. If you purchase the water meter on your own, you can expect to pay $50 to $100.

How Much Rainwater Can Be Collected?

The amount of rainwater you can collect with this type of system depends on the type and size of system you use. If you place a rain barrel beneath your gutters, you are limited to the maximum capacity of the barrel, which is usually about 50 to 60 gallons. If you want a much larger wet or dry system with a large storage tank, they are available in sizes from 1,000 to 15,000 gallons or more in capacity.

Also, the amount of water collected depends on the size of your collection area. For each inch of rain that falls, about 550 gallons of rainwater can be collected for every 1,000 square feet of space. So, larger collection areas collect more water on average.

What Can Harvested Rainwater Be Used for?

Collected rainwater can be used for watering lawns and landscaping, and it can also be treated and used to supplement your municipal supply by using it for washing machines and other in-home uses. In some cases, where the law allows, you can even treat rainwater and use it for drinking, but many areas do not allow this practice.

Stored rainwater can also be used for toilet flushing and taking showers, and in some cases, when using a first-flush system, rainwater may also be used for bathing. To ensure the water is safe for these household purposes, it is vital to keep it away from light and contaminants and use a strong filter in your rainwater system.

The way a rainwater collection system works is by consolidating rainwater from rooftops. Rainwater systems redirect water from gutters and downspouts and hold water in a storage tank. The system has some form of distribution, which can be as simple as a spigot and hose and as elaborate as a full irrigation system that’s integrated into the municipal supply.

An average household rooftop is about 2,000 sq. ft. Annual rainfall varies dramatically based on where you live in the country, but you can expect to collect about 0.62 gallons of rainwater per square foot of rooftop per inch of rainwater. Look up your area’s average annual rainfall to determine how much rain you might collect during the course of the year.

Rainwater Harvesting vs Greywater Recycling

Greywater recycling is another method of collecting and reusing water. This method involves recycling wastewater from home appliances like your washing machine or bath. The ultimate goal of both these methods is to minimize waste and promote recycling of water, but they differ greatly. Since it is collected from sinks and appliances, greywater is often filled with all kinds of chemicals and can include things like soap, detergent, and toothpaste, as well as human matter like hair and skin cells. Therefore, it is very unsafe in its unfiltered state and must be thoroughly disinfected and filtered. Even with cleaning, greywater is sometimes considered unsafe to be used on plants or gardens and is only really suitable for toilet flushing. If you want to use the water for things like bathing, drinking, or irrigation, it is best to opt for a rainwater harvesting system.

Rainwater Collection System Maintenance

Rainwater collection systems do require some regular maintenance. Gutters and filters need to be cleaned, and all components should be inspected to ensure that all parts are in proper working order. This is something you can do yourself or have an experienced landscaper come out and take care of. Landscapers will charge by the hour ($50 to $100), and you should have your system checked every season. Visually inspect your system after any rain to ensure that filters are not clogged. Tank cleaning, quality testing, and upgrades may also be part of your maintenance list. The water can also be treated through boiling, direct sunlight, chlorination, or chlorine tablets. This ensures the best quality water is used in the home.

Additional Considerations and Costs

• Connecting to public water supply. If you intend to connect your rainwater harvesting system to the public water supply, check your local regulations. Not all municipalities allow for this, and those that do require special permits and the consent of the operator of the local water supply system. Consult your local government before installing your rain harvesting system.
• Tax incentives. Depending on where you live, there may be tax incentives for installing a water collection system. Tax credits, deductions, or exemptions may be available at the state, or even city, level. Check your local guidelines or contact your town’s municipal offices for details.
• Other ways of saving water. Harvesting rainwater isn’t the only way to save water. Here are a few other things you can do as well: take shorter showers, install low-flow toilets and showerheads, wash full loads of clothes, water your lawn in the early morning or evening, don’t overwater your plants, and use drip irrigation systems.
• Warranty. Some of these systems include a warranty, giving peace of mind that the components will work for several years. In other cases, specific parts might have a warranty. For instance, some pumps have a one-year to ten-year warranty, while different tanks can have warranties that last as long as three decades. Check the warranties before buying so you have a full understanding of your available options.
• Rebates. Homeowners may be able to reduce the rainwater harvesting system price by looking into available rebates. For instance, Tucson, Arizona, offers rebates of up to $2,000 for these systems if you take a free greywater-harvesting class. Some areas in Missouri have also offered 50 cents per gallon rebates for water barrels. Check for rebates in your location to see if you have money-saving options.
• Piping inspection. No state or federal standards are in place for rainwater harvesting systems. However, many states have rules regarding the use of these systems in tandem with public water supply systems. For instance, in Texas, cross-connection safeguards must be in place to separate harvested rainwater from drinking water. These rules vary based on location. In some areas, a pipe inspection or other tasks may be needed to install the system to public water systems. The best way to be sure is to contact the country or local officials about the requirements in your area.