In this last of 4 posts on disinfection byproducts in swimming pools, we wanted to focus on the good news.  You can do something about DBPs! A lot of this is just simply good management, some is education, and some is technology.

Back to the MAHC

Before we get into the nuts and bolts, it is useful to remind everyone that the Model Aquatic Health Code (see a brief summary of the MAHC) is a broad-based effort to recommend standards for pool management.  It may have started as a response to the outbreaks of Cryptosporidium parvum in 2006 and 2007, but the procedures and technologies recommended by the Code will help to control DBPs as well.

However, as Angela Spivey points out in a nice survey article, there is no federal regulation of swimming pools and the MAHC will not result in that.  The EPA’s mandate is the natural environment, not the man-made one of pools, so standards for public aquatic venues are set by the multitude of state and local jurisdictions.

Spivey points out the experience of Tracynda Davis, who is now at the National Swimming Pool Foundation (which was instrumental in getting the MAHC process set up), when she tried to get statewide pool maintenance standards into Wisconsin law. In the end, she was forced to exclude many pools such as hotels which were then not subject to any guidelines or assistance in maintaining pool water quality.

In some ways, you are on your own.  But the things to do to maintain better water are pretty clear.

Water Maintenance is the Foundation

One thing we have learned in looking at swimming pools and DBPs is that pool maintenance is key to clean water. In a study by the Centers for Disease Control and Prevention that looked at 111,000 public pools across America, fully 12% were closed because they were unsafe. In almost every case, these pools could have been kept open by better maintenance.

The maintenance factors are well-known to aquatics professionals:

• Maintain water chemistry, especially free available chlorine (in chlorine sanitized pools, which is most pools) and pH. On many occasions, pools were found with inadequate free available chlorine (FAC).  Chlorine or an alternative disinfectant at too low a level might actually result in higher concentrations of DBPs because the precursor factors are not being oxidized.
• Monitor water temperature because it has direct effects on the chemical activity in the pool.
• Maintain pool mechanicals. Studies have shown how the failure of systems, such as ventilation, led to increased levels of DBPs in indoor pools.
• Encourage good hygiene among swimmers (see next). And, if you control it, manage the pool’s use to enforce it, e.g., close the pool for 10 minutes every hour to encourage bathroom breaks.

Teach Swimmers about Hygiene in the Pool

It is kind of amazing, but a survey of adult swimmers found that about 20% admitted to peeing in the pool at some time. The link between the nitrogen-rich urea and DBPs is well known, so we obviously have a problem here.  One thing you do NOT want to do is post a sign like one pool did to “make sure to use the bathroom before you get in the pool because taking breaks during the swim is disruptive.”

The actions swimmers can take to keep pools clean are also well known:

• Shower before you get in the pool
• Take bathroom breaks and do NOT pee in the pool
• Avoid wearing lotions or cosmetics in the pool

Use Advanced Technology to Help Disinfect the Pool

The emerging MAHC guidelines recommend ozone or UV as secondary disinfection for public pools of all kinds, and mandate it for some (like therapy pools or pools where a lot of small children congregate).

At DEL Ozone, we have reviewed the effectiveness of ozone vs. UV carefully, and we remain convinced that corona discharge ozone systems are far superior. You can and should review these two systems side by side, but we believe you will come to the same conclusion.

Ozone and UV can both disrupt chloramines, for example, but only ozone is an effective oxidant to combat the precursor organic compounds that can turn into DBPs.  We have a complete comparison of ozone vs. UV at our aquatics website.

We Can (Almost) Eliminate DBPs

At the end of these posts on pools and disinfection byproducts, we have to conclude on the optimistic note that we can practically eliminate DBPs.  We say ‘practically’ because there is still so much to learn.  But we do know that the known byproducts of chlorine, bromine, ozone, UV and other disinfectants can be controlled by systematic behavior changes and better disinfection routines.  The increasingly important combination of ozone with a low level of chlorine is an obvious path.

Taking these actions will improve swimmer health and keep swimming as one of the most beneficial exercises available.

Previous posts:

This is the 4th of four posts on disinfection byproducts and their threat to swimmers.  To read all of them, follow the links:

1. A brief history on the emergence of disinfection byproducts as a health hazard.

2. Sources of common DBPs in drinking water, and in pools.

3. Brief review of the accumulating evidence showing disinfection byproducts can be a health threat.