Why Well Water Turned Brown When Filling a Pool

Water Wells

• According to Wellowner.org, almost half of the people in the U.S. depend on ground water from wells for their domestic water. The source of the water in the well is from what is called ground water, water that moves through the soil and rock and is collected in the well. As the ground water filters through the soil and rock, it collects the minerals and chemicals that are found naturally there. Many of these minerals will dissolve in the ground water, altering the water's chemical composition. Common minerals found in well water are iron, calcium and magnesium. These metal minerals can react to chemical-disinfecting pool additives, causing your pool water to turn brown.

Pool Additives

• Pool owners add chlorine to the water to disinfect and kill any harmful microorganisms, algae and bacteria. Periodically, a treatment of super-chlorine is indicated, referred to as shock, to free up the initial chlorine, which, over time, joins with the ammonia and nitrogen in the water, rendering it less effective as a disinfectant.

Results

• Your well water may appear clear as it comes out of your garden hose, but likely the water contains microscopic iron particles. The addition of chlorine into your pool oxidizes the iron particles, coloring them brown or reddish-brown and turning your pool water brown. The brown pool water will not harm swimmers, but will adhere to swim clothing and skin, with possible staining. The iron particles will eventually settle to the bottom of the pool, if the water is not circulated, and be vacuumed away. This method is time consuming, and there are faster and more effective methods to clear your pool water.

Solutions

• Preventive measures can avoid the problem of your pool water turning brown. Get your well water tested prior to filling your pool to determine the mineral content. A metal trap filter that attaches to the end of your hose will collect the iron particles before they enter your pool. If you have already filled your pool, added chlorine and discovered the iron oxidation, attach cotton socks over the filters, hose heads and a cotton towel over the jets. Every hour change the socks and towels. You will see the iron particles trapped in the socks and towels. While the system is being filtered, vacuum the iron particles that have collected on the bottom of the pool. Several replacements of the sock and towels may be required before your pool water is clear, but this method is safe, with no additional chemicals.