Week of August 5, 2002
By Calvin Finch, Conservation Manager, San Antonio Water System, and Horticulturist

  WATER SOURCES FOR PLANTS

            Fluoride-treated water works just as well as water without fluoride. The levels of fluoride that will soon be in all SAWS and Bexar Met water will not be high enough to have any effect on our plants. This has been proven in many tests and by the experiences of other cities that have used fluoride for several generations.

            Rainwater is very high quality water for plants. Rainwater is naturally acidic and often contains small levels of nitrogen, both characteristics that result in superior plant performance. Collect rainwater from your roof in a rain barrel for use in container plants. For information on rain barrel use write: Rain Barrels, SAWS, Conservation Division, P.O. Box 2449, San Antonio, TX 78298-2449; or visit the website plantanswers.com.

            Air-conditioning condensate is also high quality water that can be used for plants. Collect it in the rain barrels just like rainwater. Condensate and rainwater work well in tandem. The most condensate is produced by our air conditioners during the hottest part of the summer when it does not rain much.

Graywater is the water produced when we use our clothes washing machines and the shower. It has soaps and other impurities in it but works fine for plant watering, especially the lawn. In San Antonio graywater can be used on your lawn if it does not puddle or leave your yard. Some new home purchasers are asking for plumbing that allows graywater use for the landscape. It is harder to use graywater in a home where the plumbing has to be altered after the fact.   

Blackwater is the sewer water from the toilet, kitchen sink, and dishwasher. It is used in some elaborate irrigation systems governed closely by the plumbing code, but not on a wide scale.

Swimming pool water can be used for irrigation. Occasionally, the pool must be backwashed and, after rains, excess water is pumped out. The levels of chlorine are high enough in pool water that a steady use of the water would hurt many types of plants, but as an occasionally source of water, most plants will not be affected. Lawn grasses are especially tolerant of chlorinated water. Pool water definitely should not be wasted by dumping it into the sanitary or storm sewer.

Even though softened water with its relatively high level of sodium is not recommended for plants, used in moderation it does not hurt them. If the salty water is used for container plants, let a portion run out the seep hole. The water leaving the pot carries much of the salt with it. Another trick is to alternate softened water with unsoftened water, or even rainwater. The higher quality waters will dilute the impact of the salty water.

San Antonio has enough water for good gardening, especially if we are resourceful and do not waste any water.