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Rain barrel · a decision

Is a rain barrel legal and worth it?

Rain barrel laws differ by state, so check yours first; where barrels are allowed, they suit garden watering, since one inch of rain on a 1,000 sq ft roof can shed about 620 gallons.

VerdictCheck rules

620 gal

gallons one inch of rain can shed off a 1,000 sq ft roof in theory (our arithmetic, TWDB's 0.62 gal/sq ft/inch)

Worth it for beds where your state allows it; check your state's limit first, and never drink it or plumb it in.

Worked out by Where Your Gallons Go from 7 dated sources · numbers checked 11 November 2026

The answer by situation

  • Colorado homeTwo barrels maxState law allows at most two barrels holding 110 gallons combined, for outdoor use on the same property.
  • Utah parcelYes, with limitsUp to 2,500 gallons a parcel; free registration if more than two containers or any over 100 gallons.
  • Texas homeYesRainwater equipment is exempt from state sales tax, and HOAs cannot ban harvesting.
  • Any other stateCheck firstEPA warns some states might prohibit collection; check your state water agency.
A red rain barrel on a brick stand beside a house wall, fed by a hose from the downspout, with a spigot at the bottom
A red rain barrel on a brick stand beside a house wall, fed by a hose from the downspout, with a spigot at the bottom

It depends on the state, and EPA's own Watering Tips page says some states "might have laws that prohibit collection of rainwater". The three states below are the ones we could confirm through a university extension or state agency page on 11 Nov 2026. For any other state, check your state water agency before buying.

How fast does a rain barrel fill?

Faster than most people expect. The Texas Water Development Board puts the theoretical catch at about 0.62 gallons for each square foot of roof, per inch of rain. By our arithmetic, a 1,000 sq ft roof sheds about 620 gallons in one inch of rain, so a single 50-gallon barrel on a downspout draining a quarter of that roof fills in about a third of an inch.

That is why the overflow matters as much as the barrel. Once full, extra water has to go somewhere away from the foundation.

Rain off a roof against barrel sizes
Roof area to the downspoutGallons per inch (theory)Inches to fill 50 galInches to fill 110 gal
250 sq ft155about 0.32about 0.71
500 sq ft310about 0.16about 0.35
1,000 sq ft620about 0.08about 0.18
2,000 sq ft1,240about 0.04about 0.09

Source under the table: Texas Water Development Board. Our arithmetic at TWDB's theoretical 0.62 gallons per sq ft per inch; TWDB says installers assume 75 to 85% of that in practice.

Is a rain barrel worth it for watering?

For a few beds or pots, yes; for a lawn, no. A landscape typically needs about one inch of water a week including rain, per EPA, and one inch over 1,000 sq ft of lawn is about 620 gallons, many barrels' worth. A barrel or two is best saved for beds, shrubs and containers between storms. For bigger beds, pair it with drip irrigation; a washer's drain water sent through laundry to landscape is a steadier supply where allowed.

Is rain barrel water safe?

Not to drink. CSU Extension says untreated roof rainwater is not safe to drink. Use it on plants, and never connect a barrel to the house plumbing or to any drinking-water pipe. Even in Texas, TWDB says harvested rainwater must be kept from any contact with the public drinking-water system.

Watch: Rain Barrel Installation Tutorial From DuPage County Stormwater Management · 2:00. Plays from YouTube only when you press play. A county stormwater office levels a solid base, raises the barrel on blocks, cuts the downspout to height, and hooks a hose to the overflow port to carry extra water away once the barrel is full.

The county clip levels a base, raises the barrel on blocks, cuts the downspout to height and hooks a hose to the overflow. Use the water on plants only; it is not for drinking and should never be connected to house plumbing.

How do I keep mosquitoes out of a rain barrel?

Seal it. The CDC says to tightly cover water storage containers, including rain barrels, and to use wire mesh with holes smaller than a mosquito where there is no lid. CSU Extension adds that a barrel should be emptied at least monthly and disconnected if you will be away more than a week.

Will a utility pay toward a rain barrel?

Some will. Austin Water offered up to $5,000 for rainwater harvesting based on storage, and Tucson Water capped storage at $1,900 with a separate $99 tree payment, both when checked on 11 Nov 2026; Tucson requires a workshop. See water utility rebates and the yard page for how barrels compare with other outdoor savings.

When the answer flips

  • You live in Colorado: the answer is yes, but only two barrels and 110 gallons in total.
  • You want more than two containers or one over 100 gallons in Utah: register first; it is free.
  • You hoped to use the water indoors: a barrel is the wrong tool; keep it outdoors, for plants only.
  • Your state is not listed here: check your state water agency before collecting any rain.

What to buy or ask a plumber

  • Look for a barrel with a sealable lid, a screened inlet and an overflow port.
  • Ask your state water agency, or in Utah the Division of Water Rights, what limits apply.
  • Ask your water utility whether it rebates barrels or cisterns, and whether a workshop is required.
  • Keep the barrel separate from every house pipe and faucet; a barrel never feeds indoor taps.

Also asked

Can I use rain barrel water on vegetables?

It is meant for watering plants, not for drinking. Untreated roof runoff is not safe to drink, so water at the soil rather than over leaves you eat, and rinse produce as you normally would.

Do rain barrels need to be emptied in winter?

Where pipes freeze, many people drain and disconnect them. CSU Extension also says to empty barrels at least monthly in season.

Are rain barrels tax exempt in Texas?

Yes. Under Texas Tax Code §151.355 you pay no state sales tax on harvesting gear, and TWDB says the buyer hands the seller an exemption form.

Can my HOA stop me from using a rain barrel in Texas?

No. Texas Property Code 202.007 stops HOAs from banning rainwater harvesting, though they may require the system to be screened from view.

How we reached this

State rules come from Colorado State University Extension (May 2025), Utah State University Extension (undated) and the Texas Water Development Board, all read on 11 Nov 2026. The Colorado and Utah statute texts were not available to confirm on 11 Nov 2026; this page relies on those two extension services' summaries. Every other state is left to its own agency. Fill times are our arithmetic from TWDB's theoretical roof yield and run high, since real systems catch 75 to 85%. Rebates change; check your utility.

Sources

  1. US EPA WaterSense — Watering Tips · some states may prohibit collection; one inch a week · checked 11 Nov 2026
  2. Colorado State University Extension — Rainwater Collection in Colorado · two barrels, 110 gallons, outdoor use, not potable, empty monthly · checked 11 Nov 2026
  3. Utah State University Extension — Rain Barrels in Utah · 2,500 gallons a parcel; registration trigger · checked 11 Nov 2026
  4. Texas Water Development Board — Rainwater Harvesting FAQ · 0.62 gal per sq ft per inch; sales tax; HOA; cross-connection rules · checked 11 Nov 2026
  5. CDC — Mosquito Control at Home · cover rain barrels; mesh · checked 11 Nov 2026
  6. Austin Water — Rebates, Tools & Programs · rainwater rebate up to $5,000 · checked 11 Nov 2026
  7. Tucson Water — Rainwater Harvesting Rebate · up to $1,900 plus $99 · checked 11 Nov 2026

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