Green Aquatics: Eco-Friendly Pool Draining

By Terry Arko


n the late '70s The Beach Boys wrote a hip save-the-environment song called "Don't Go Near the Water." Though the lyrics were timely, they seem even more poignant today: "Don't go near the water, don't you think it's sad. What's happened to the water? Our water's going bad… Oceans, rivers, lakes and streams have all been touched by man. The poison floating out to sea, now threatens life on land."

While swimming pools aren't specifically called out in these lyrics, when drained, they can unfortunately become a contributor to the pollution and degradation of our waterways and oceans. As pool professionals, it is imperative that we make every effort possible to minimize the pool's environmental impact, especially when releasing water during draining.

Nutrient Overloading

According to the U.S. Geological Survey, 80 percent of the earth's surface is water. Ninety-seven percent of the water on earth is saltwater in oceans and seas. Three percent of the water is fresh, and only 1 percent of that is available for use. The problem is that today much of the water available for use is being threatened by something known as "nutrient overloading."

When lakes, rivers and streams become overwhelmed with the byproducts of increased agriculture and industry, the result is an influx of algae enriching nutrients. The primary culprits in nutrient overloading are nitrogen and phosphates. Phosphates are classified as a primary growth nutrient for algae, and when there is abundance in the waterways, excessive algae is the result. When an overabundance of algae in lakes occurs, dissolved oxygen levels decrease and fish begin to die off. When this nutrient-rich water reaches our oceans via streams and rivers, it causes persistent red tides made up of toxic algae. This toxic algae along ocean shorelines is responsible for killing off marine mammals and fish. It is also known to cause severe skin rashes and even respiratory illness when human contact occurs.

A recent and very vivid example of nutrient overloading is the prolific algae bloom that clogged the 2008 Olympic sailing venues off the coast of Qingdao, China. The blooms occurred in a heavily industrialized region of the Yellow Sea where untreated sewage from costal cities and high levels of nitrates from agricultural and industrial runoff feed into the sea.

Many environmental experts agree that the only way to solve the increasing algae problems is to find ways to limit the amounts of nutrient pollutants entering our lakes, rivers and streams.

Pool Chemicals' Impact

For those who are working in the swimming pool industry, it's important to understand the impact swimming pools can have upon our earth's water system. When backwashing or draining, whatever is in the water eventually gets deposited into our waterways. Some examples of what can end up in our water system when pools are drained include: chlorine, phosphates, nitrates, calcium hardness, high TDS, bacteria and protozoa, acidic water and salt.

All of these, individually or combined, can have a vast impact upon the aquarian environment, leading to possible fish kills, excessive algae, increased salinity and overall harm to the water. Because of this, many state and local environmental agencies regulate how, when and where swimming pools can be drained. It is the pool professionals' responsibility to know the local regulations for pool draining.

Many areas have strict requirements for lowering chlorine levels and buffering acidic water. Others do not allow draining into storm drains or gutters. There are even some requirements that forbid pool water from touching any properties other than the property where the pool is located. So, it would be against the law if any of the water from a particular pool were to spill over into an adjacent property.

Many pools are now using salt chlorine generator systems to sanitize. Pool pros should always do their homework and check the regulations for draining these types of pools. Some areas forbid the draining of salt generator pool water into their system. For example, Santa Clarita, Calif., was one of the first areas to develop a law forbidding the draining of salt generator pools into the sewer to prevent an increased level of salinity in the Santa Clara River.

Eco-Friendly Recommendations

When preparing to drain a pool, the first step is to evaluate the condition of the water. Is the water properly balanced? Has the pool been properly sanitized, or is it a swamp? Is the chlorine high? Does it contain high levels of metals or salts? Has it been tested and treated for phosphates?

If the water hasn't been sanitized recently or is in a swamp condition, then the pool should be superchlorinated to deal with bacteria, algae and organic matter. If draining to the sewer is permitted, then you may not need to superchlorinate as the water will be treated at the municipal plant. If you do superchlorinate to clean up the pool before draining, you should try to get the chlorine to 30 ppm and hold it for 12 hours. This will inactivate most bacteria and protozoa that can be present.

Before draining, the water should be dechlorinated. The best way to achieve this is to allow several days before draining so the water can lower the chlorine level naturally. If this is not possible, the pool can be dechlorinated using sodium thiosulfate.

Once the pool has been dechlorinated, you should test for phosphates and, if needed, treat to lower the phosphates to at least 200 ppb before discharging. As mentioned earlier, phosphates are a prime pollutant to our waterways and are responsible for numerous algae outbreaks in lakes and streams. Treating for phosphates is a simple eco-friendly practice that will help minimize a pool's environmental impact during draining.

After treating for phosphates, the pool should be treated with a good natural-based clarifier and filtered for at least 24 hours. Look for products that are oil-free and non-synthetic.

Once it is time to drain, check the hydrostatic pressure. Before draining, make sure the pool has a hydrostatic relief valve that relieves pressure from possible groundwater. At a minimum, you should always know what the water table level is for the particular area in which you are draining. Failure to check this could lead to literally popping the pool out of the ground. This can cause major damage and expense.

If you are not able to drain to the sewer, consider draining in a grassy area such as a field, as this will provide natural filtration to remove many chemicals and nutrients that may still be present in the water.

It Starts With You

Always be a conscientious drainer! Make sure you are doing your part to ensure the water you are about to put back into the open water system is as clean and pure as possible. Like The Beach Boys say in their song, let's all "be cool with the water."


Terry Arko has worked in the pool and spa industry for over 25 years, in service, equipment repair, retail management and chemical manufacturing. A Certified Pool/Spa Operator, he has spent the past 14 years as a technical consultant specialist in the area of chemical water treatment. He currently is a products specialist for SeaKlear Pool and Spa Products in Bothell, Wash. For more information, visit

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