The Ultimate Solution for Suction Entrapment

An Interview by Eric Herman

For more than 30 years, Dr. William N. Rowley — founder and principle of Rowley International, headquartered in Palos Verdes Estates, Calif. — has worked tirelessly to address the causes of suction entrapment incidents. He has personally investigated scores of cases, has served as an expert witness in numerous resulting lawsuits and has conducted multiple research projects studying these often-horrific events.

applying what he’s learned in his work designing commercial pools and aquatic facilities the world over, Dr. Rowley has devised systems that are as safe as possible. The result? Of the literally millions of people who have immersed themselves in pools he has designed, not one has ever been the victim of entrapment.

Now, as the effects of the Virginia Graeme Baker Pool & Spa Safety Act (VGB Act) are being felt throughout the aquatic realm, we checked in with Dr. Rowley for some historical perspective and his take on where the industry stands in trying to eliminate suction entrapment accidents.

When you first looked at this problem back in the 1970s, what did you learn about suction entrapment in your initial rounds of investigation and testing?

Back in those days, I was working with SwimQuip, one of the industry’s leading pool-and-spa equipment manufacturers at the time. We were already working on some health code revisions when we were contacted by officials at the International Association of Plumbing & Mechanical Officials. There had been a suction-entrapment drowning death — a child in Orange County — and they were trying to figure out exactly what had happened.

We investigated the accident and started doing some calculations based on biometrics and modeling. We came to the conclusion that we needed to study the issue using a live model. That was the first time I volunteered to use my own body for the purpose. We immediately discovered that under all the conditions we tested — including various flow rates and types of outlet fittings — if the cover or grate was properly attached and intact, I could easily free myself simply by rolling off the grate. I did so with very little effort; I didn’t even use my arms or legs for leverage.

Why is this issue so confounding for so many people?

It should be fairly simple, really, because we know how to prevent suction entrapment with proper flow rates, secure fittings and split drains. Or with no drains at all. The reason it’s seemingly so complicated is because there are so many people involved on so many levels. And some of them are primarily concerned with selling products, so they may see the safety issue as secondary.

That’s a tough charge.

It is. And of course, no one wants to appear to be callous when it comes to safety. But when you’re in the trenches on this issue as I have been all these many years, and you watch the behavior of some of those involved, you can’t come to any other conclusion: They’re really only there to use this incredibly serious issue as a way to gain an advantageous position in the marketplace.

Can you be more specific?

Let’s look at the manufacturers of suction vacuum-release systems (SVRS). I’ve been at odds with a handful of representatives of these companies for years because of the way they market their products.

We know those devices won’t stop limb entrapment accidents because by the time they work, the victim’s arm or leg is already lodged in the plumbing.

They don’t stop hair entanglements, either. This is the most common type of entrapment accident in the presence of SVRS systems. The flow is never completely blocked, so these devices don’t “know” to turn off the system. Moreover, they won’t work on large commercial systems because the suction forces are too great. And being mechanical, there’s always a chance of failure — especially if the device is not maintained or calibrated properly.

And finally, they do not stop eviscerations. These accidents, which involve tearing of the lower intestine or colon, happen almost instantaneously. Because of the dynamics of hydraulic systems, SVRS devices simply cannot react in time to prevent these terrible accidents. (For the record, manufacturers of these devices do not claim that their systems will prevent eviscerations.)

Thus, of the four identified types of entrapment accidents, the SVRS systems do not prevent three of them.

Are there situations where one of these devices might save someone? Absolutely, and I’ve never said they have no use. But we need to be realistic about the narrow range of situations in which these devices can be effective — and that’s not how these companies have positioned their products.

You’ve been a proponent of split main drains. Why?

As far as we know, there’s never been any kind of suction entrapment incident on a properly functioning, code-compliant, split main drain. I’m not saying that there isn’t some extreme condition or unusual circumstance where it couldn’t happen, but there’s no documented case of which I’m aware.

No matter whether you look at it from an engineering standpoint or just plain common sense, it’s obvious that split drains reduce the risk to such infinitesimally small levels that they can be considered an effective method of prevention.

When you combine proper flow rates with secure, code-compliant grates or covers, you’ve effectively solved the problem.

Then why do some argue against their use?

Maybe it’s because they remove the need for an SVRS device or relegate it to a purely secondary measure. The people who make those devices don’t want to hear that — or for others to start to see it that way.

One of the terms that comes up in VGB rules and in recommendations by organizations such as the U.S. Consumer Products Safety Commission is “unblockable drain.” What exactly does that mean?

When the American Society of Mechanical Engineers and the American National Standards Institute were working on their standards, they came up with what is known as the 99-percentile man — meaning human dimensions that are equal to or bigger than 99 percent of all people. That fellow is 75.6 inches tall and weighs 244 pounds. In their testing using models, it was determined that he could block a drain that is 18 inches wide and 23 inches tall.

Unfortunately, they didn’t do any human testing, which I’m certain would have dramatically influenced the findings because of the way the human body moves when it’s stuck. We don’t pull ourselves straight off, but instead roll off. When you break the suction on one side, you basically peel off the drain like a postage stamp. As a result, I would say that the resulting codes are much harsher than they need to be because they don’t take into account the supple and flexible nature of the human body.

Again, when you perform tests with live subjects, you immediately learn that if the grate or drain cover is in place, you can roll right off. It doesn’t matter if it’s an antivortex cover or a basic grate: If it’s intact and securely attached, you will be able to free yourself.

Overall, has the VGB Act helped or been a step backwards?

I think it’s helped because it has forced everyone down the line — from health inspectors to contractors and end users — to take a serious look at the problem and in many cases correct potentially hazardous situations. Specifically, a number of non-compliant grates that might potentially have been hazardous have been replaced.

As with anything the government produces, the language can be confusing and even contradictory, so it has its problems.

Ironically, the actual accident that prompted the act in the first place occurred in a residential spa, which is where the vast majority of suction entrapment accidents happen. Despite that fact, the law addresses commercial installations only, so it doesn’t even address residential pools or spas.

Still, I think the measure has been helpful.

In your opinion, what’s the ultimate solution to the problem?

The most effective measure is one that is not accepted or even considered by most health department officials: It’s time that we start eliminating main drains altogether in pools and spas, both commercial and residential.

This is a classic case of tradition trumping common sense. Pools can function perfectly well without main drains — which really aren’t even drains at all, but really are just bottom suction outlets. Pools are normally drained using sump pumps, not their drains. And it’s been shown time and again that main drains are not necessary for proper circulation. (Consider also that aboveground pools have never used main drains and operate without problems.)

From my own experience in designing commercial pools for all types of applications, I know that they function beautifully without main drains. In many systems, we’re now using floor inlets that do a wonderful of job of dispersing chemicals and enhancing energy efficiency for heating. So why not simply eliminate the risk by eliminating the place where suction entrapment occurs: on the main drain.

If you look at it from a risk-analysis standpoint, risk is exposure times the hazard. In this case, the hazard is the drain itself; if you remove it altogether, you’ve eliminated the risk. The reason spas are riskier is that the exposure is greater because bathers are closer to the drain. So again, eliminate the main drain and place the suction outlets in skimmers and gutters where they pose virtually no risk. Then the problem goes away.

Are there other advantages to eliminating main drains?

eliminating main drains, you also eliminate the cost of installing them in the first place. That may not amount to much in a residential pool or spa, but in a 50-meter competition pool, a drain can cost upwards of $50,000. In addition, you eliminate the cost of remodeling them. We’re finding that many facilities with large pools simply do not have the wherewithal to remodel their pools into compliance, so they face closing down. That whole set of problems goes away when you eliminate the drain.

Compounding the problem is that health departments have never thought about these issues in this way before and are notoriously slow in changing directions. Despite the resistance, there is absolutely no downside to eliminating main drains and everything to gain.

Considering all the years of controversy, research and tragedy, what you’re suggesting seems almost too simple a solution.

In my opinion, this problem has never been as complex as it’s been made out to be. When you participate in lawsuits as an expert witness, you learn just how convoluted it can become when skilled attorneys get hold of this issue. But that doesn’t change the laws of physics — and in this case, nobody can deny that you cannot get stuck on a drain that does not exist.

If we’re truly serious about eliminating suction entrapment, we have to get rid of single-suction main drains, period. They can be dangerous and are obsolete. Until we do so, I’m afraid this issue will continue to be with us to some degree, no matter how much the current crop of regulations, standards and recommendations help.

When we do decide to get rid of main drains, we’ll say goodbye to suction entrapment once and for all. That is probably easier said than done, but it’s entirely possible and, I believe, necessary in technical, ethical and even moral terms.

Dr. William N. Rowley , Founder and Chairman of the Board of Rowley International Inc., has been directly responsible for the design of over 600 major swimming pool complexes worldwide. A registered and licensed Professional Engineer (PE) in the State of California, the District of Columbia, and 27 other states, Dr. Rowley is a Certified Safety Professional (CSP), as well as a licensed California General Engineering Contractor, a California General Plumbing Contractor and a California General Solar Contractor. For more information, go to www.rowleyinternational.com.

Eric Herman is the editor of WaterShapes.