Though it’s illegal to discharge swimming pool/spa backwash and drainage water off your property, in general you can dump this water into the public sewers. You can also reuse this water to help your thirsty plants!
Emptying a Pool/Spa the Plant-Friendly Way:

Draining an Aboveground Pool/Spa

  1. Stop adding chemicals to the pool/spa water. Wait half a week. The pH level of the water should fall between 7 and 8 and chlorine
  2. content should be 1 part per million (1 milligram/Liter) or less before water is discharged. Water should be clear and free of algae.
  3. Rent an electric pump or use a siphon line (see over).
  4. Place the intake hose in the pool/spa and the outlet hose in the center of your yard or landscaping.
  5. Plug in and turn on the pump, priming per the manufacturer’s recommendations. Move hose around and run until landscaping is saturated. Turn off pump and wait until the water has seeped in.
  6. Restart pump.
  7. Repeat until drained.

Draining a Sunken Pool/Spa

  1. Stop adding chemicals to the water. Wait half a week. For highly chlorinated pools/spas, you may need to wait longer for the pH level to reach between 7 and 8 and chlorine content to fall to 1 part per million or less. Water should be clear and free of algae.
  2. Find the drain line (usually near pump motor) in the filter pump.
  3. Attach a long hose to the drain line. Run the other end of the hose to your yard, concentrating drainage on landscaping and high water-use trees.
  4. Moving hose if needed, run pump until landscaping is saturated.
  5. Turn off the pump and wait several hours.
  6. Repeat until pool is empty.

Draining with a Siphon Line

Instead of using an electric pump, a siphon line can be used to drain above-ground pools and in-ground pools where the land slopes away. To use the siphon method, submerge and fill the pool vacuum hose or a garden hose with water. Cover one end tightly, and pull it out of the pool and below the pool water level. It will drain itself. Spas can be drained this same way.

Using Swimming Pool/Spa Water on Plants

Drainage of pools and spas is usually done infrequently to carry out repairs or correct water chemistry (usually every 5-7 years for pools and 2 years for spas). Backwashing, the cleaning of pool/spa cartridge or sand filters, is part of more regular maintenance. This backwashing water (approximately 75 gallons each rinse), and pool/spa drainage water, may be used to irrigate a variety of salt-tolerant plants

Perennial Plants That Tolerate Salty Soil

There are very few small garden plants that tolerate salty soil in high concentrations.

  • Blanket Flower
  • Daylily
  • Lantana
  • Prickly Pear Cactus
  • Lavender
  • Cotton
  • Seaside Goldenrod

Moderately Salt Tolerant Perennial Plants

There are very few small garden plants that tolerate salty soil in high concentrations.

  • Yarrow
  • Agapanthus
  • Sea Thrift
  • Candytuft
  • Hardy Ice Plant
  • Cheddar Pinks (Dianthus)
  • Mexican Heather

Other Water-Saving Tips for Pools and Spas

Lower the water level in your pool to reduce loss due to splash. Cover your pool or spa when it’s not in use. This reduces evaporation and has the added benefit of warming up the water during cooler Tucson months.