Can You Use Untested Well Water to Fill Your Swimming Pool?

Potential Contaminants

• Well water can contain a variety of chemicals, minerals and contaminants that water from a city reservoir may not have. The pH levels of well water can vary greatly, and pH is one of the key factors in ensuring all pool chemicals work together efficiently. Nitrate levels in well water are often higher than in city water, and can enter the water from sources like agricultural runoff and wastewater. Depending on the location of the well, the water may also contain chemicals and pollutants from nearby commercial and industrial facilities. Well water can also contain high amounts of minerals like sulfur, manganese and iron. By not testing the water before filling the pool, pool chemicals will be mixed with an unknown combination of contaminants.

Associated Problems

• Without testing for pH levels, it will be impossible to achieve the desired alkalinity in the water. If the pH is not between accepted levels of 7.2 and 7.8, the other pool chemicals will not be able to work together to sanitize and clean the water. Well water can contain minerals that will discolor and stain the pool. Using well water in a pool without neutralizing these minerals can result in red, brown or black staining that can be difficult, if not impossible, to remove. Untested well water can also make swimmers ill, as the water can contain bacteria like E. coli or other parasites.

Benefits of Testing

• While well water can be used just as efficiently in pools as city water, it needs to be tested first. Testing allows the homeowner to immediately take steps to adjust the pH balance to ensure the pool chemicals work together from the beginning before more problems develop. If minerals are present in the water, there are chemicals that can be added to get rid of the minerals and prevent staining. Once the pool is filled with well water and allowed to sit to see what problems develop, it can be extremely difficult to fix the compounded problems. This is especially true with vinyl pools; these pools should not be completely drained after filling because of the possibility of damage to the liner, so testing and preventing problems is extremely important.

Salt Water Pools

• Although salt water pools may seem more of a natural option than a standard pool, well water should also be tested before being used in this type of pool. While the chemical interactions in salt water pools may be less noticeable than those in standard pools, well water that contains minerals such as sulfur will still release an unpleasant odor. Many salt water pools use titanium attachments and plates, which can be adversely affected by well water that has high levels of calcium. Buildup from the minerals in the water can begin to clog the pool's system, requiring frequent cleaning and raising the maintenance level considerably.