Gaia

Water Harvesting Calculators

Every drop counts in the desert. Calculate how much free water you can capture.

The roof formula is arithmetic. The olla, mulch and laundry figures are rules of thumb and say so; they are being checked against extension sources and will carry them when they do.

A rain chain feeding a clay cistern beside a desert house at dusk, a drip line running to a bed of peppers

Roof to cistern to bed. The oldest plumbing there is.

Illustration

Roof Rainwater Catchment

How much free water falls on your roof each year?

Formula: sqft × inches × 0.623 = gallons

Olla Sizing

How many buried clay pots for your garden bed?

Mulch Water Savings

How much water does 3-4" of mulch save?

Laundry Greywater

New Mexico allows residential greywater reuse without a permit up to 250 gallons a day under 20.7.3 NMAC; other states differ, so check yours.

Buried Pot Reservoir System

A homemade cousin of the olla: sealed pots stuffed with cotton, buried under the beds. A workshop method, not a trialled one; the olla above has the longer record.

Build method: Seal bottom holes → heat nail for pin-prick holes in upper 1/3 → stuff with old cotton clothes → line hole with black construction bag → bury 8-10" deep → cap with flat rock → cover with soil → plant above