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Prepping for a drought (Part 4): Alternative sources

By The SHTF App Team

In a severe drought, municipal water restrictions can become draconian. You may be banned from watering your garden entirely, watching your food-producing plants wither and die. But while the city tap might run dry, you have two massive, untapped reservoirs right on your property: the rain that falls on your roof and the water that drains from your washing machine.

Capturing rainwater and recycling greywater are the ultimate acts of self-reliance. They decouple your landscape’s survival from the municipal grid. Instead of paying for premium drinking water to dump on the ground, you use resources that are currently being wasted. The first summer we ran the laundry-to-landscape line, our fig tree got fat and happy on water we had already used once. It felt like cheating. The city had banned outdoor watering, the hose was coiled and useless, and yet twenty gallons a week of washing-machine water was going into mulch basins around the fruit trees, legally, because the rules for greywater were different from the rules for tap. The tree did not care that the water was secondhand. Trees never do.

In a severe drought, municipal restrictions can become draconian: you may be banned from watering your garden entirely and watch your food-producing plants wither. But while the city tap might run dry, you have two massive untapped reservoirs right on your property: the rain that falls on your roof, and the water that drains from your washing machine. Capturing rainwater and recycling greywater are the ultimate acts of self-reliance. They decouple your landscape’s survival from the municipal grid.

This is Part 4 of the drought series, and it is about tapping the sky and the drain.

Disclaimer: The information provided in this article is for general informational and educational purposes only. It is not intended as, and should not be considered, legal or plumbing advice. Laws regarding rainwater harvesting and greywater differ drastically by state and county. Always consult local codes before cutting pipes.

The Readiness Audit

Does your property harvest what falls on it and drains out of it?

  • Green: You have a screened rain barrel or tank on a downspout, and your washing machine feeds mulch basins through a diverter.
  • Yellow: You know your roof would yield a lot of water but nothing captures it, and your laundry water goes straight to the sewer.
  • Red: You have never calculated how much rain your roof sheds in a single storm.

If you are Yellow or Red, execute Phase 1 immediately.

Phase 1: Rainwater Harvesting (Catching the Sky)

Goal: Turn your roof into a reservoir.

Rainwater is free, mostly clean, and plants love it because it lacks the chlorine and fluoride found in tap water.

  • The math: roof square feet × rainfall (inches) × 0.623 = gallons harvested. A 1,000 sq ft roof in a 1-inch storm yields 623 gallons.
  • Level 1, the rain barrel: place a 55-gallon drum under a downspout with a spigot at the bottom and an overflow hose at the top (directed away from the house). Cover the inlet with fine mesh to prevent mosquitoes from breeding.
  • Level 2, the first-flush diverter: the first few gallons of rain wash bird droppings, pollen, and dust off your roof. A first-flush diverter captures those first gallons in a separate pipe, sealing them off so only clean water enters your storage tank.

The Takeaway: Run the math for your own roof before buying anything. Most people are one inch of rain away from hundreds of gallons they are currently giving to the storm drain.

Phase 2: Greywater Recycling (The Laundry Loop)

Goal: Use the washing machine’s pump to irrigate for free.

Greywater is the gentle wastewater: dirty, but not toxic. The washing machine is the easiest place to start because it has its own built-in pump.

  • The system (laundry-to-landscape): install a 3-way brass diverter valve behind the washer. Position A sends water to the sewer (for diapers or greasy rags), Position B sends it to a 1-inch irrigation line running to your garden.
  • The outlet: the water dumps into mulch basins (holes filled with wood chips) around trees and bushes, where the mulch filters the water before it hits the roots.
  • The soap audit: standard detergents are full of salts (sodium) and boron that build up in the soil and kill plants. Switch to liquid, biocompatible detergents (like Oasis or Ecos) and avoid powdered soaps and softeners.

The Takeaway: The diverter valve plus biocompatible soap is the whole system. Twenty loads a month is hundreds of gallons your trees get instead of the sewer.

Phase 3: Greywater Rules of Engagement (Safety)

Goal: Reuse water without creating a biology problem.

  • No storage: greywater contains skin cells and bacteria. If you put it in a tank, it rots. It must go immediately from source to soil.
  • No contact: greywater is for roots, not leaves. Do not spray it, dump it under the mulch.
  • No root vegetables: do not use greywater on carrots, potatoes, or radishes (anything you eat raw that touches the dirt). Use it for fruit trees, bushes, and ornamentals.

The Takeaway: Greywater goes underground, immediately, onto things that do not feed you raw. Three rules, no exceptions.

Phase 4: The AC Condensate Hack

Goal: Harvest the water your air conditioner is already wringing out of the air.

In hot, humid climates, your air conditioner acts as a dehumidifier, pulling gallons of water out of the air daily. Find the drip line outside your house (usually near the condenser unit) and place a bucket under it. On a humid day, an AC unit can generate 5 to 20 gallons of distilled-quality water, excellent for watering plants or flushing toilets.

The Takeaway: This is the laziest harvest in preparedness. The machine runs anyway. All you add is a bucket.

The Essential Kit Checklist

  • The legal check: search “rainwater harvesting laws [your state]” and “greywater codes [your county]” today.
  • The detergent switch: check your laundry soap. If it has sodium, boron, or borax, buy a biocompatible replacement.
  • The AC check: locate your air conditioner’s drip line and test the yield with a bucket.
  • The calculation: estimate your roof size to see how many gallons a single inch of rain would give you.

Scenario Planner (Contingencies)

“Rainwater harvesting is illegal where I live.” The trap: assuming the whole state has one rule. The fix: rules vary drastically by state and county, and many restrictive states have loosened for rain barrels specifically. Check your county code before writing it off.

“My greywater smells after a week in the barrel.” The trap: storing greywater, which always fails. The fix: no storage, ever. The water goes source-to-soil within 24 hours. If it cannot reach soil immediately, send it to the sewer that day.

Next Steps

  1. Do the roof math tonight. Square footage × 0.623 is your harvest per inch of rain, and it is usually a shock.
  2. Check the detergent bottle. Sodium or boron on the label means your soil is one load away from damage, so swap it before installing anything.
  3. Read Part 5: The storage protocol next, because harvesting water is only half the security: keeping it drinkable for months is the other half.

Originally adapted from public EPA and state water-board rainwater and greywater guidance (public domain).