Swimming Pool Blog

Swimming Pool Filter Safety

Common Pool Equipment Repairs
by Rob Cox January 16, 2014

Swimming Pool Filter Safety

Pool filter maintenance & repair

When we were out servicing pools, with our old service company Cox Pool & Spa Services, I had a manager named Mark, who had his right arm shattered in 7 places by an exploding pool filter. If any of our readers are former customers, you may remember the full arm cast Mark wore around for 9 months.

A closed valve after the filter allowed filter pressure to build up inside the tank until the top half broke free from the belly band clamp, and it shot straight up, through Mark's arm. It also took off about 6" of the roof eave on its way up.

Swimming pool equipment safety isn't a topic that's discussed much anymore. Manufacturers have improved filter designs to nearly prevent most injuries. But there are still a lot of older, unsafe pool filters installed on pools, owned by homeowners unaware of the potential danger.

Pool Filters can be dangerous vessels - because they are under strong pressure. Leaks can foreshadow failure, if a full blown tank rupture occurs. If the clamp band fails while under pressure, or isn't securely fastened, the top of the filter can blow off violently. And not always straight up, sometimes the filter top blows off sideways.Old Sta-Rite DES filter

The filter that exploded on Mark was an old Sta-Rite vertical DE filter, shown right. Good filter, but unsafe. He could have had the clamp band positioned incorrectly, or the band wasn't tight enough, or the belly band o-ring was not sealing properly. What actually happened was a minor miscalculation; a closed valve after the filter, causing the lid to blow off under the pressure.

The clamp bands of older clam shell type (with two halves) pool filters are smaller, maybe a third of the thickness and weight of modern clamp bands. The threaded tightening assembly has also been vastly improved on new and much safer clamp bands for DE and Cartridge filters.

old style pool filters can be dangerous!If your pool filter has a skinny clamp band, like those shown here in the picture, you should replace the filter with a new model by Hayward, Pentair or Jandy.

It's not a matter of IF the band clamp will fail, it's a matter of WHEN. Spot welds will fail, threads will strip, and o-rings will slip - eventually.

 Jim Halverson, killed by a pool filter

In 2009, Jim Halverson was in the backyard of his California home. What happened exactly next is not clear, but the two piece pool filter blew apart, and Jim was struck in the head, knocking him unconscious. Jim died later of his injuries. story

The CPSC has reports of several other fatalities since the early 80's, and dozens of injuries have been reported. I suspect that hundreds of other injuries have gone unreported (like Mark's).

Triton sand filter domeAnother injury can occur with sand filters. Old style Pac-Fab Triton filters have threads cut into the fiberglass tank which can strip, allowing the dome lid of the filter to pop off. The domes used to be clear, and you could look inside. They are now opaque - why? Because people kept getting their face right up against the filter dome, and become injured when the dome popped off.

New sand filter models also use a molded flange collar now, which has virtually eliminated the problem. In fact now it's more common that the entire sand tank may rupture before the lid blows off. Top mounted multiport lids can blow off too, although the connected pipes may help hold it down.

That reminds me of a story....I had a crew out opening a pool with a TR-100 sand filter. The system was started up, but the return plugs were still in the wall. Pressure built up (with no one watching the pressure gauge), until the fiberglass filter tank split, with a loud bang! Water was spraying everywhere, and there were piles of sand on top of the pump motor. No one was hurt, but hearts were racing - and it cost the company a new filter :-( 

Modern Pool Filters

New pool filters, those manufactured from the late 90's until now, have been redesigned to be safer, with modified tank halves and very sturdy clamp bands - and several new safety labels to warn of the potential dangers. Old parts for unsafe pool filters are largely unavailable, as smart manufacturers have simply quit making them. If you find yourself with a filter from the 80's or 90's, it may be time to replace your pool filter with a newer, safer generation.

Really, I'm not trying to sell filters - I'm trying to prevent accidents. No matter what type of pool filter you have, here are some pool filter safety tips to practice, which may help you avoid the danger, even if your tank is not the safest pool filter out there.

10 Pool Filter Safety Tips

  1. Always check downstream plumbing for any closed valves or plugs in returns before starting pump.
  2. Always open air bleeder valve on your filter before starting up the pump, or when draining the filter.
  3. Keep a hand on the switch, and  eye on the pressure gauge when starting pump.
  4. Always clean the o-ring and center the clamp band equally over both tank halves.
  5. Tap the clamp band around its edge while tightening, and be sure it is tightened fully and evenly.
  6. Fix Leaks on the filter clamp, dome, drain assembly or bulkhead fittings. Replace leaking tanks.
  7. Never use a filter pump with flow rates higher than the filter design flow rate.
  8. Replace damaged parts noticed for your clamp band or filter tank top.
  9. Never lean over the filter, Always stand away from the filter.
  10. Replace pressure gauges when they become unreliable or broken.


- Rob