Is a Rainwater Cistern Right for Your Property?

Rainwater harvesting offers a dual benefit: it reduces stormwater runoff leaving your property while simultaneously cutting your demand for treated municipal water. By capturing rain from impervious surfaces—most commonly rooftops—you create a reserve for later garden irrigation.

This approach saves money on water bills and allows moisture to infiltrate your landscape instead of flowing into storm drains. Below, we explore rainwater catchment systems to help you decide if a cistern suits your needs.

Cistern vs. Rain Barrel: Understanding the Difference

Homeowners typically choose between two catchment options: cisterns and rain barrels. Cisterns are large tanks capable of holding up to 20,000 gallons in residential settings, while standard rain barrels hold about 55 gallons.

Due to their size, cisterns require professional design and installation, whereas rain barrels are DIY-friendly, affordable, and compact. Barrels are always above ground; cisterns can be installed above or below grade.

Why Choose a Cistern?

A high-capacity cistern stores significantly more water, delivering greater watershed benefits. Cisterns and barrels can complement other sustainable stormwater features like rain gardens and swales. When weighing a cistern against a barrel, consider these factors:

Pros

• Stores water for extended dry periods
• Modular—additional cisterns can be added later if space and budget allow
• Can potentially eliminate potable water use for entire landscape irrigation
• Integrates with greywater systems to further reduce household water consumption
• Flexible installation: above or below ground

Cons

• Requires substantial space
• High upfront cost
• Needs professional installation due to size and complexity
• Units over 5,000 gallons require engineered structural support at the base
• Prohibited in Colorado (redirect roof runoff to a rain garden instead)

Cost Breakdown

An 800-gallon cistern ranges from $500 to $1,000 depending on material. A 20,000-gallon system with a concrete foundation can exceed $20,000, excluding labor. Large, high-end cisterns designed for whole-house and landscape offset require architect and engineer collaboration.

Underground installations add excavation costs and are engineered case-by-case with a landscape architect and engineer.

Sizing Your Cistern

Capacity depends on your harvest goals, available space, and budget. Tools like Texas A&M University’s rainwater harvesting calculator can help; have a professional verify the numbers. The supplier will often confirm calculations as well.

Qualified professionals include master plumbers, green builders, LEED-certified experts, landscape architects, and building architects specializing in sustainable design.

Key System Components

Most suppliers offer kits with all necessary parts:

• Water holding tank (cistern): Collects and stores rainwater
• Cover or lid: Keeps tank airtight but removable for maintenance
• Leaf and mosquito screen: Prevents debris and insects at the inlet
• Overflow mechanism: Directs excess water—consider routing to a rain garden

Cistern Materials

Large cisterns become visual features. Smaller units can be screened; larger ones should complement your home’s architecture and landscape. All cisterns must be opaque to prevent algae growth.

Popular materials:

• Concrete: Pre-cast or cast-in-place; naturally reduces water acidity over time
• Metal: Strong, lightweight; requires galvanization and a plastic liner
• Polyethylene: Most affordable and widely available; less aesthetic
• Plastic: Budget-friendly but typically lasts ~25 years
• Wood (with plastic liner): Attractive but pricier and less common

A wood barrel-style cistern with coordinated red metal bands that echo the shed door and shutters.

A metal-roofed home with a stone facade; the oversized cistern mirrors that aesthetic with a corrugated metal top and stone-clad base wall.

Placement Guidelines

Consult your architect or landscape architect. General rules:

• Check local codes for setbacks and permits—cisterns are often classified as landscape structures
• Place near the collection point (e.g., a downspout) for cost efficiency
• Position uphill from the irrigation zone to use gravity flow, avoiding pumps

Using Collected Water

Roof runoff is best applied to non-edible landscape plants—lawns, trees, flower beds, and ornamental gardens.

Show us: Have you incorporated a cistern into your landscape? Share photos in the comments.