A cistern water system can be a great way to collect and store rainwater for household use. With concerns over water shortages and the cost of city water rising, more homeowners are considering cisterns to supplement their water supply. But cisterns aren’t inexpensive. Let’s take a look at what factors affect the cost of installing a cistern system for a house.
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What is a cistern?
A cistern is a large tank used to collect and store rainwater that falls on a roof or other surface. The water can then be used for non-potable purposes like irrigation, toilet flushing, laundry, and other household needs. Cisterns are often made out of concrete, plastic, or fiberglass.
A complete cistern system includes the storage tank, pipes and gutters to collect rainwater, a pump and filtration system, and additional plumbing to distribute the water for use in the home. The cistern tank is connected to the existing plumbing system but kept entirely separate from the main water supply.
Cost factors
There are several factors that affect the overall cost of installing a cistern water system:
Size of the cistern tank
The size of the storage tank is the biggest cost factor. Cistern tanks range greatly in size from 500 gallons up to 30,000 gallons or more. The bigger the tank, the more rainwater you can collect and store. But larger tanks cost more.
For a single-family residential home, a common cistern size is between 2,500 and 5,000 gallons. This size provides enough capacity to supplement non-potable household water needs. Expect to pay the following for the cistern tank based on size:
Tank size | Cost |
---|---|
500 gallons | $1,000 – $2,000 |
1,000 gallons | $1,500 – $3,000 |
2,500 gallons | $3,000 – $5,000 |
5,000 gallons | $5,000 – $8,000 |
10,000 gallons | $10,000 – $15,000 |
Material of the cistern tank
Cisterns can be constructed from concrete, polyethylene plastic, corrugated steel, or fiberglass. Concrete and polyethylene are the most common options for residential installations.
Concrete cisterns are more expensive initially but very durable. Plastic tanks are cheaper but have a shorter lifespan. Fiberglass is lightweight and moderately priced. Expect to pay:
- Concrete: $3,000 – $6,000 for a 2,500 gallon tank
- Polyethylene: $1,500 – $3,000 for a 2,500 gallon tank
- Fiberglass: $2,000 – $4,000 for a 2,500 gallon tank
Excavation and site prep
For underground cisterns, cost for excavation and preparing the site for the tank installation can add $2,000 or more. The excavation work depends on soil conditions and accessibility.
Pumps and plumbing
You’ll need a pump to distribute the stored water into the home’s plumbing system. Plus additional piping, valves, filters, and other plumbing components. This can cost $1,500 to $4,000 depending on the specifics.
Gutters and drainage
To collect rainwater, the home’s existing gutters and downspouts may need to be enlarged or supplemented. This can cost $1,000 or more in materials and installation.
Permits and installation
Factor $500 to $2,000 for permitting fees and professional installation services. The total depends on local permit rates and labor costs.
Total cost for a house
Taking all these factors into account, a typical total cost to install a complete cistern system for a house can range from:
- Small system: $5,000 – $10,000 for a 500 to 1,500 gallon storage capacity
- Medium system: $10,000 – $20,000 for a 2,500 to 5,000 gallon storage capacity
- Large system: $20,000 – $40,000+ for a 10,000+ gallon storage capacity
Get quotes from several cistern installation contractors to compare costs for your specific project requirements. Be sure to maximize potential rebates and incentives that can help offset the upfront cost.
Factors that affect water savings
While the upfront cost is significant, a properly sized cistern can provide great water savings over time. The actual savings depend on several factors:
Rainfall in your area
The more annual rainfall your location receives, the more water a cistern can collect, and the more you’ll save on your water bill. An area with 40 inches of rain can collect over 20,000 gallons of rainwater per year from a moderate sized home. Drier climates with less precipitation will yield less savings.
Roof collection area
The larger the roof area draining to your gutter system, the more rainwater you can collect. A 2,000 square foot roof can generate over 30,000 gallons of water per year in many regions. Maximize your catchment area to get the most out of your cistern system.
Water usage
Your savings are also tied to how much rainwater your household can use productively, instead of relying on municipal or well water. Using stored rainwater for irrigation, laundry and flushing toilets has the biggest impact. Gardening and landscaping needs also boost potential savings.
Water rates
The cost you pay per gallon of drinking water from your city or private well impacts savings. If your rates are low, savings will be less. But in places with expensive water, a cistern can deliver bigger returns.
Incentives and rebates
Many municipalities offer rebates and incentives to install rainwater harvesting systems, which improves the payback. For example, you may get 25% of the system cost back. This reduces the payback period.
Payback period
With a total installed cost from $10,000 to $30,000 or more for a house, how many years will it take for a cistern system to pay for itself through water savings?
In optimal conditions with high water rates, significant rainfall, and maximum water collection and usage, a home cistern can provide payback in 5-10 years. 10-15 years is more typical. Larger cisterns for maximum storage capacity provide better payback but are a bigger upfront investment.
Here are three examples of payback period for home cistern systems under different rainfall, usage, and water rate scenarios:
Example 1 | Example 2 | Example 3 |
---|---|---|
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|
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Payback Period: 12 years |
Payback Period: 8 years |
Payback Period: 14 years |
Cistern systems provide the best payback in regions with expensive water, low rainfall to maximize collection potential, and homeowners willing to use the rainwater for maximum benefit.
Maintenance
While cisterns are passive systems requiring little maintenance, some annual upkeep is required:
- Inspect gutters and roof washouts and clean out debris
- Check seals, pipes and valves for leaks
- Inspect the pump and filtration system
- Clean out the tank periodically
Proper maintenance will maximize water quality and extend the life of your cistern. Budget $200 to $300 per year for maintenance costs.
Conclusion
Installing a cistern to harvest rainwater is a significant investment, with total costs ranging from $10,000 to $40,000+ for a complete system. The payback period can be over 10 years. But in the right conditions, you can save substantially on household water costs while benefiting the environment. To get the best return, maximize water collection area, storage capacity, and usage. Compare quotes to find the best value installation. Take advantage of any rebates or incentives. And consider complementing cisterns with other water-saving fixtures and appliances to maximize savings.