Swimming Pool Suction Entrapment
August 1, 2022
I am a pool geek.
I can’t help myself. I LOVE swimming pools. Whenever I see a pool I have to check it out and see how it works and figure out flow rates (Fred Hare of Sta-Rite water-hydraulics fame was right!) And, I have to make sure it’s safe for kids to swim. This is a story about a potential suction entrapment hazard I came across.
Last week I traveled to Maui for a wedding. On the morning of the big event, I sat for breakfast at a cozy little restaurant that was right next to the hotel pool and had a great view of the ocean. I ordered my food and while it was being prepared I did what I do: I walked over to the pool to admire it and see how it was built. It had an awesome surface that was completely done in penny tiles. They had the name of the resort spelled out in tiles along with a lazy river in mosaics. What workmanship! So cool! Then I saw it: exposed and uncovered skimmer equalizer lines- a cardinal sin in the swimming pool industry.
I bent down and removed one of the skimmer lids. Maybe the equalizer line in the skimmer was plugged and that open pipe on the pool wall was a moot point? Nope, it was wide open. At least there wasn’t a skimmer float valve in the skimmer so the likelihood of water getting sucked from the equalizer line was nil. I returned to my seat and enjoyed the best banana macadamia nut pancakes I’ve ever had. Oh my they were good. Fluffy. Full of nuts. Fresh bananas. And the coconut syrup was warm! There was little chance that I would finish these four giant pancakes… but I did. They were so good I couldn’t help myself. You know that feeling- you feel guilty because you’re full but you keep eating it anyways because it tastes sooooo good. I am a pool geek and today I am a gluten.
I think I lost myself in those pancakes because I was torn over what to do. Should I notify the hotel staff? Should I write a letter? Should I report the pool? I finished my breakfast, left a healthy tip in appreciation of my wonderful meal and waddled back to the pool. While I decided what to do I started taking photos. Just as I took the last photo an over-protective hotel maintenance employee snapped at me. “Hey, what are you doing?! You can’t take photos! You need approval from the engineering department!”, he yelled at me with his thick Hawaiin accent. Okay I thought, I guess I’m not going to notify the hotel staff today, this guy is not in a mental space to listen. It was an abrupt mood alteration from the peaceful Hawaiin morning I was enjoying. Gosh, that guy could have handled that so much better. Greeting me and asking what I was up to would have been a much better approach. I could tell he wasn’t in any mood to listen so I didn’t even bother. I said I’m sorry and walked away (although I got a kick out of seeing him taking photos of me). The poor guy I thought, he’s probably worried that I’m some howlie inspector who’s going to write him up for some code violation…
As I walked back to my room I decided that a blog post would be the best approach- I can share the issues and educate anyone interested in this subject and then email the link to the hotel management in hopes that they will make the appropriate repairs to make the situation safe. Here goes:
How can a skimmer equalizer be dangerous?
The following image shows how a pool can be plumbed to suck water from the equalizer line
(here’s the link to Wine Country Pools. They have a great article on how these things work).
Water gets sucked from the skimmer to the pump. The back hole in the skimmer (the one furthest from the pool wall) is where water enters and goes to the pump, through the filter, etc. Because commercial pools (hotels, apartment complexes, community pools, health clubs…) have to meet certain turnover rates determined by the health department, the flow through these pipes can differ from one pool to another. The greater the flow, the greater the “differential hold-down force“. Or, in layman’s terms, the greater the flow, the more ability the pump has to hold you against an uncovered suction pipe, also known Suction Entrapment. And, when someone gets trapped against one of these pipes, injury is certain and death is likely.
Preventing Suction Entrapment
The swimming pool industry prevents suction entrapment primarily by using specially designed plastic drain covers. There are all particular specifications to determine proper sizing of drain covers and sumps but I’m not going to discuss formulas in this article. The bottom line is if you don’t completely understand them, get a professional who does- Lives are literally at stake.
In 2007 the United States adopted federal laws regarding swimming pools known as the VGB Act. It was named after a little girl who became entrapped and drowned.
Two well-written suction entrapment articles can be found here:
The Maui Pool
I found four skimmers on this pool ( there could be more, these are the ones I took photos of). All four skimmers had equalizer pipes below them on the wall. Two of them had drain covers covering the equalizer pipes/ ports/ lines), two of them did not. The two that did not are my concern.
How to make this pool safe from suction entrapment
There are different ways to make this pool safe from suction entrapment. Commercial pools are overseen by the Health Department in their county. I have found that each health dept. enforces the VGB Act differently. In this specific case, I am not as concerned with codes as much as I am about getting this pool safe ASAP.
- Cover the exposed pipe openings with drain covers per the federal VGB Act.
This could be done by draining the pool, cutting that beautiful tile and cementing in a drain cover (this is unlikely as there are other less expensive options available)
- Cover the openings with drain cover fittings that are made to slip into the existing pipe (I always epoxy them when I use these).
Aquastar out of San Diego makes a wide assortment of drain covers to meet many different needs.
I could see the 615SI101 6″ Sumpless Bulkhead Fitting with 1.5″ Slip Insider working with a 6HPHA101 cover over it.
This would work on the deep-end skimmer but wouldn’t fit under the skimmer at the steps so something else would be needed on that one
- Plug the hole inside the skimmer with a 1.5″ threaded male plug.
It doesn’t have to be exactly like the one in my image, I just picked oneThis would be my method. It will cost less than $2 per fitting. Wrap some teflon tape around it, thread it in the equalizer hole and Shazam! no more suction issues from the equalizers
For those technical geeks out there (like me)
I know, if you look at the photo there isn’t a float valve in the skimmer…. My response? Who cares! Maybe the pool maintenance person took them out because they flooded and they are on order? Also, have you ever found suction from an equalizer line without a float valve present? I have. When there are lots of leaves in the pool the leaves fill the skimmer basket and act just like a float valve: they clog up the basket and the pump sucks from the path of least resistance. It can’t suck from the top of the skimmer because of all the leaves in the basket so it sucks from the front hole, the equalizer pipe. Have you ever seen a towel floating in a pool? Of course you have- especially at an apartment complex. I’ve seen towels clog the basket and activate the equalizer pipe. How about plastic wrappers? Yep. Garbage bags? Yep.
Plugging that equalizer hole inside the skimmer is the fastest and least expensive way to prevent suction from that equalizer pipe.
To the hotel management:
I purposely didn’t mention your hotel name because I highly doubt this is a malicious or even careless oversight. The pool has probably been that way for years without any incidents and issues like this can be easily overlooked unless you have an eye for it. I mean no harm, I just want to protect children, the public (and your company) from injury.
Accidents are just that: accidents. They aren’t common but when the stars are aligned they can happen.
Mike the Poolman