How much free water hits your roof every year?
Enter your Austin home address. We'll estimate how much rainwater your roof could capture and score your property. No signup to see your number.
We don't install anything
RainwaterIQ is an independent Austin rainwater assessment. We use your address to estimate what your roof could capture, from public rainfall data and your building's footprint, and we show you the number before asking for your email. If you decide you want quotes from local installers later, you can make that call on your own timeline.
Three steps. About a minute. No account.
You see a real, property-specific estimate before we ask for your email.
Enter your address
The only thing we need to start. No name, no phone, no signup.
We look up your roof and your rainfall
We look for building geometry, use a labeled estimate if it is unavailable, and apply Austin's long-term rainfall normal.
You get your number
Estimated gallons your roof could capture in a year, plus a 0–100 Rainwater Potential Score that explains what's driving it.
The math, in the open
Your estimate uses a documented formula and assumptions. This is how it is built.
Gallons ≈ your roof footprint × Austin rainfall × 0.623 × collection efficiency
0.623 gallons per inch, per square foot
One inch of rain drops this much water on one square foot of roof. It's the standard industry constant, the same one the Texas Water Development Board uses.
Austin rainfall: about 36.25 inches a year
We use the NOAA 1991–2020 30-year climate normal for the Austin–Camp Mabry station, a long-record central Austin station, rather than a single wet or dry year. The number stays stable and reproducible. We use this station across the Austin metro. Rainfall at your property and in any single year will vary.
Collection efficiency: about 85%
Real systems never capture every drop. First-flush diversion, gutter spillage, and overflow all take a share. The 85% factor is an assumption, not a simulation of your tank. Actual usable water depends on rainfall timing, storage, and demand.
Your roof footprint, not a city average
Where available, footprint comes from City of Austin 2023 building geometry, so the estimate is specific to your property. When measured geometry isn't available for an address, we fall back to an estimate and label it clearly on your result.
Sources: NOAA NCEI U.S. Climate Normals (1991–2020), Austin–Camp Mabry station; Texas Water Development Board rainwater harvesting guidance; City of Austin 2023 building footprints. Rebate and regulation figures are date-stamped and flagged for review when their review dates pass.
A few things worth knowing before you start
Austin-specific facts behind the estimate, each one sourced.
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A 2,000-sq-ft Austin roof could capture about 38,400 gallons a year using the 36.25-inch Camp Mabry rainfall normal, 0.623 gallons per inch per square foot, and 85% collection efficiency. This is a worked example, not an average Austin roof.
Sources: NOAA 1991–2020 climate normals and Texas Water Development Board rainwater harvesting guidance.
- Austin Water: Residential Rainwater Harvesting Rebate Up to $5,000 (capacity-based)
Austin currently offers qualifying rainwater-harvesting rebates of up to $5,000. Eligibility and the final rebate amount depend on system design, storage capacity, and program requirements.
Rebate requires meeting Austin Water program rules; pre-approval and specific system criteria typically apply. Confirm current terms before purchasing.
Source: Austin Water: Water Conservation Rebates · verified 2026-08-30
- Stormwater / Drainage Charge Reduction ~$2.90-$4.90/month (example, tank-size dependent)
Capturing rainwater on-site may qualify your property for a modest monthly drainage (stormwater) charge reduction, often a few dollars per month for a ~1,000-gallon tank.
Drainage-charge reductions depend on impervious-cover and program criteria; amounts vary.
Source: City of Austin: Drainage Charge · verified 2026-08-30
- Texas Rainwater Harvesting Incentives & Protections Sales-tax exemption on equipment
Texas actively encourages rainwater harvesting: rainwater-harvesting equipment is exempt from state sales tax, and state law limits how HOAs can restrict residential systems.
Exemptions and HOA protections have specific statutory conditions; verify current rules.
Source: Texas Water Development Board: Rainwater Harvesting · verified 2026-08-30
Incentives and rules change. These are educational summaries with sources and last-verified dates (latest: 2026-08-30). Confirm current terms before purchasing. We never guarantee eligibility or a specific amount.
Questions homeowners ask
How much rainwater can my roof collect in Austin?
In Austin, a roof collects about 0.623 gallons per square foot for every inch of rain. With the Austin–Camp Mabry ~36.25" annual rainfall normal (NOAA 1991–2020) and a typical residential collection efficiency of about 85%, a 2,000 sq ft roof could realistically capture roughly 38,400 gallons per year. Enter your address for a property-specific estimate.
How much water does one inch of rain produce from my roof?
One inch of rain yields about 0.623 gallons per square foot of horizontal roof footprint. A 2,000 sq ft roof produces roughly 1,246 gallons per inch of rain before system losses.
Does Austin offer a rainwater harvesting rebate?
Austin currently offers qualifying rainwater-harvesting rebates of up to $5,000. Eligibility and the final rebate amount depend on system design, storage capacity, and program requirements. Confirm eligibility and current terms with Austin Water before purchasing.
Is rainwater harvesting legal in Texas?
Texas actively encourages rainwater harvesting: rainwater-harvesting equipment is exempt from state sales tax, and state law limits how HOAs can restrict residential systems. Statutory conditions apply; confirm current rules before planning a system.
See what your roof can do
Enter your Austin address for a property-specific estimate. No account required.
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