Filtering Pool Water

Filtering Pool Water 1

Many people have inquired if they can filter their pool water with a PortaWell® system to make it safe for drinking in an emergency. Here are the things to consider:

The first thing to know is that if you have a saltwater pool, the PortaWell® system and filters do not remove salt (sodium chloride) from water or other hard water minerals such as calcium and magnesium. Because salt is a dissolved solid, the most common method to remove salt from water is through reverse osmosis filtration.

Now is you don’t have a salt water pool, your pool water can be great water source for filtering through PortaWell if you know what chemicals have been used for its maintenance.

Most pool chemistry is adequately controlled using chlorine tablets or using auto controllers that maintain the pool chemistry by injecting hydrochloric acid for PH control and sodium hypochlorite (bleach) for free chlorine levels.

Chlorine tablets typically have Tricoloro-S-Triazinetrione as it’s main ingredient. This provides free chlorine for control of algae and biologics (bacteria and virus) and cyanuric acid which acts as a stabilizer for the chlorine against sunlight. (Free Chlorine quickly breaks down in the presence of sunlight without a stabilizer present). EPA chlorine limits for drinking water is <4 ppm (parts per million) and <20 ppm for cyanuric acid. A properly maintained swimming pool is <4 ppm chlorine but the cyanuric acid concentration can be up to 70 to 90 ppm or even higher.  Unlike chlorine which dissipates over time, cyanuric acid builds up  and the only practical method to reduce its concentration is to dilute or replace the pool water.

An activated carbon filter is effective for reducing low concentrations of chlorine and cyanuric acid. My swimming pool had a cyanuric acid concentration of 70 ppm and after filtering through the charcoal filter it was reduced to < 15 ppm; a good filter combination for filtering my pool water is the ceramic filter in the first stage and the activated carbon  filter in the 2nd stage. A chlorine kit and cyanuric test strips can be purchased (recommended if you are considering using your pool water for an emergency water supply) from pool supply stores or websites to verify the filtered water meets EPA limits for those two chemicals. I check my pool regularly and if the cyanuric acid concentration goes above 70 ppm it is time to change the water.  

If the pool has been regularly treated with some proprietary algicide or if there is significant algae in the water because the circulation pumps have been off for a long period, then the treatment strategy becomes a little more complicated. You may need to pretreat the water to remove the algae so it doesn’t prematurely plug the filters and you may need to select a different filter to remove the more exotic chemicals in the algicide. Commercial filters are available that fit PortaWell® which contain media especially suited for reduction of heavy metals and a broader spectrum of organic chemicals. We offer the AquaCera CERAMETIX filter that reduces >92% of heavy metals and reduces( >90%) a wide range of other organic chemicals.

If my pool water is clear and I know the cyanuric acid level is less than 70 ppm,  I am very comfortable using my pool as a source of water for drinking and cooking after it has been filtered through my PortaWell. 

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