Is a Rainwater Cistern Right for You?
These extra-large containers reduce runoff and save on the use of potable water for the landscape
Falon Mihalic
October 12, 2015
Houzz Contributor. Landscape Architect in Texas and Florida and owner of Falon Land Studio LLC. Through landscape design, I create spaces for quiet reflection and lush gardens using native plant palettes and sustainable stormwater techniques. I'm a contributing writer to Houzz so that I can be active in the conversation about sustainable design for residential projects. Learn more about my company's work at falonland.com
Houzz Contributor. Landscape Architect in Texas and Florida and owner of Falon Land... More
Rainwater harvesting does two great things at once: It reduces the amount of stormwater runoff sent downstream and simultaneously reduces your potable water demand. Essentially, you collect rainwater from an impervious (also called nonpervious) surface — most often a rooftop — to use for watering your garden later.
It’s a win for everyone, because you can save money on your water bill and also allow water to infiltrate your property instead of heading offsite through storm drains. Read on to learn more about rainwater catchment systems and decide if you’re ready to take the plunge.
It’s a win for everyone, because you can save money on your water bill and also allow water to infiltrate your property instead of heading offsite through storm drains. Read on to learn more about rainwater catchment systems and decide if you’re ready to take the plunge.
Cistern versus rain barrel. There are two types of rainwater catchment systems for homeowners: the cistern and the rain barrel. Cisterns are large tanks that can hold up to 20,000 gallons of water in residential settings, while a standard rain barrel is smaller, usually holding about 55 gallons.
Because of their size, cisterns are more of an undertaking than rain barrels and benefit from professional advice and help with installation. Everyone can install a rain barrel. They take up very little space and are quite affordable. The barrels are always placed above ground, while a cistern can go above or below.
Read more about the benefits of rain barrels
Because of their size, cisterns are more of an undertaking than rain barrels and benefit from professional advice and help with installation. Everyone can install a rain barrel. They take up very little space and are quite affordable. The barrels are always placed above ground, while a cistern can go above or below.
Read more about the benefits of rain barrels
Why use a cistern? One advantage of choosing a super-sized cistern over a rain barrel is that it lets you store more water, resulting in a greater benefit to watershed health. Cisterns and rain barrels can be used in conjunction with other sustainable stormwater techniques in the landscape, such as rain gardens and swales. When evaluating whether to choose a cistern over a rain barrel, consider the following:
Pros
Cons
Pros
- Cisterns store more water for longer periods
- Potential to add additional cisterns later if space and budget allow
- Potentially eliminate the use of potable water irrigation for your entire landscape
- Can be integrated with greywater reuse systems to reduce your home’s overall water use
- Can be installed underground or above ground
Cons
- Require a large amount of space
- Large initial investment
- Require professional installation help because of their size
- Cisterns over 5,000 gallons in capacity also need structural support at their base
- Prohibited in Colorado; instead you can redirect roof rainwater to a rain garden for infiltration
How much does it cost? On the low end, an 800-gallon cistern can cost anywhere from $500 to $1,000, depending on the material you choose. On the high end, an extra-large cistern with a 20,000-gallon capacity and structural concrete foundation can cost up to $20,000, not including the labor to install it.
Large-scale, high-end cisterns are usually used for offsetting the amount of potable water used inside the home and for the landscape and need to be designed in consultation with an architect and engineer.
An underground cistern requires excavation, which also adds to the cost. Underground cisterns are designed on a case-by-case basis and in consultation with an engineer and landscape architect.
Large-scale, high-end cisterns are usually used for offsetting the amount of potable water used inside the home and for the landscape and need to be designed in consultation with an architect and engineer.
An underground cistern requires excavation, which also adds to the cost. Underground cisterns are designed on a case-by-case basis and in consultation with an engineer and landscape architect.
Sizing your cistern. The size of your cistern depends on how much rainwater you want to harvest, how much space you have and how much money you want to invest.
Sizing a cistern can be done with a rainwater harvesting tool, like this one from Texas A&M University. Have someone double-check your calculations, and talk with the company selling you the cistern; it will likely confirm the calculations for you.
You can also hire a design professional or green building professional to help you choose the cistern that’s best for you. Among the types of professionals who can help: master plumbers, green builders, LEED-certified professionals, landscape architects and building architects. Look for professionals who specialize in green, sustainable building and design.
Sizing a cistern can be done with a rainwater harvesting tool, like this one from Texas A&M University. Have someone double-check your calculations, and talk with the company selling you the cistern; it will likely confirm the calculations for you.
You can also hire a design professional or green building professional to help you choose the cistern that’s best for you. Among the types of professionals who can help: master plumbers, green builders, LEED-certified professionals, landscape architects and building architects. Look for professionals who specialize in green, sustainable building and design.
Key components of a cistern. Companies that sell cisterns usually also sell kits that include the system components you need to get fully up and running. Here are the main components of a cistern system:
- Water holding tank (cistern): Collects and stores the rainwater for later use
- Cover or lid: Keeps tank airtight, but can be removed for maintenance
- Leaf and mosquito screen: Placed at the water inlet to keep leaves and bugs out of the tank
- Overflow mechanism: Allows water to overflow through a directed pipe; consider sending your overflow to a rain garden
Cistern materials. Because cisterns are quite large, they can make a statement in the yard. You could tuck a smaller cistern behind a wall or lush hedge. For an extra-large cistern, however, you’ll want to coordinate the material with your home’s landscape and architecture. It’s not that the cistern needs to match the home, but it should be chosen and placed in a way that complements the house and landscape. All cisterns should be completely opaque to prohibit algae growth.
Popular materials for cisterns include:
Popular materials for cisterns include:
- Concrete: Can be pre-cast or cast in place; a major advantage is that concrete reduces the water’s acidity over time
- Metal: Strong and lightweight; needs to be galvanized and contain a plastic liner
- Polyethylene: Most affordable and most readily available cistern material; not particularly attractive
- Plastic: Affordable but has only a 25-year life span in most cases
- Wood (with a plastic liner): More aesthetically pleasing but also more expensive and not as readily available
This home has a metal roof with a natural stone facade, and the extra-large cistern is designed to have a similar style with a corrugated metal top and natural stone facade on the low wall surround.
Where to place your cistern. Placement should be done in consultation with your architect or in consultation with your landscape architect if the cistern is for storing roof runoff. Some general guidelines are as follows:
The wood barrel-style cistern shown here has coordinated materials and colors. Notice how the red metal bands on the cistern play nicely with the red shed door and mini-shutters.
- Check with your local building code on setbacks and regulations. A cistern will probably be treated as a “landscape structure” and may require a permit.
- The most cost-effective location will be closest to the source point for the water to be stored — for example, next to a downspout that collects roof runoff.
- It’s easiest to place the cistern uphill from where the water will be used. This eliminates the need for pumping the water, allowing gravity to do the work for you.
The wood barrel-style cistern shown here has coordinated materials and colors. Notice how the red metal bands on the cistern play nicely with the red shed door and mini-shutters.
Uses for collected water. Collected roof runoff is best used on nonedible landscape plants. You can use the water to irrigate your lawn, trees, flower beds and more.
Show us: Have you incorporated a cistern into your landscape? Upload pictures in the Comments.
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Show us: Have you incorporated a cistern into your landscape? Upload pictures in the Comments.
More
To Manage Stormwater Sustainably, Understand Your Site
Discover more ways to save water
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As you say, beauty and ugliness are subjective. But for me, galvanised metal will never be in the least attractive, any more than a grey, concrete slab is. They both have their place, e.g. as part of a farm building or industrial unit. The current "fashion" for them in cities or suburbs will "date" and they'll be torn out or covered up one day. Wait and see.
Very good article, sharing as well. Thank you.
I live in the Virgin Islands. Water is precious here and we are a water-conscious people.
We have 40"+ annual rainfall that falls sporadically, arriving all at once via tropical weather systems during hurricane season or from November through January,
which is our rainy season. It can get very dry and we can go 4-6 months with no rain.
We do not have basements in our houses, instead that space becomes the cistern.
All houses must be built with integral concrete cisterns for water storage.
In the past there were above-ground brick cisterns, later built in block or cement.
Each house has a water pump to draw water up from the cistern for use.
There is no mains water available unless you live close to town. Mains water,
aka town water, (obtained from reverse osmosis & stored in reservoirs), is used
to refill cisterns during our frequent droughts. The alternative is having water
trucked in at great expense.
Roofing is designed to maximize rainwater collection with downspouts leading into
cisterns. These can range in size from 20,000 - 60,000 gallons, or even larger, if
you can afford them. Cisterns are accessed through concrete lids in the floor.
They have interior partial walls allowing one to switch from an empty section to
a full section. Empty sections should be cleaned on a regular basis.
In 2017, after Hurricanes Irma & Maria, some of islands were without power
for 6 months - no water pump working - but we still had water with bucket and
rope via cistern lids in floors. Puerto Rico has no cisterns and relies on mains water.
In the aftermath of the storms, without electricity to make desalinated water or pump
to homes, people there suffered terribly, and many died.
It is my opinion that every house should have a cistern, and that every commercial building should have a cistern, even on the mainland. With the rapid growth of
population, and changes in climate patterns, people cannot rely on wells or municipal
water supplies. We need to be able to rely on rainfall collected and stored in cisterns.
Grey water cisterns can store used water, provided it is not contaminated with faeces
or chemicals, and that grey water can be used in gardens. Black water has to pass
filtration beds to be rendered suitable for grey water use.
Water is so vital to life - Do not ever take it for granted.