How often do they change pool water completely?

Former Member
Former Member
Anyone knows how public swimming pools are maintained? Do they completely change the pool water at the end of day, or weekly? Anything they do to the pool overnight (just circulate like daytime, or do nothing, or change entire pool water)? Is the water cleaner in early morning than evening because of this? Thanks.
  • I just sent an email to and called the Evanston health department about the local LA Fitness pool. I'm convinced they have no idea how to maintain the damn thing. I doubt it's clean in the morning or the evening. I'm never going back there again. (PM me if you want details.) Skip
  • I know that at my school, we check the water every hour. I believe that is NY State law. We change the water twice a year. The board of health comes around periodically to check our logs.
  • at my Y, it is changed once a year. But, they are a little lazy on putting fresh water in the pool and thus, the pool gets extremely cloudy. At Villanova, it is probably changed sometime in the summer. All I know whether they change or not, it is a very clean pool. Sometimes, the pool temperature is higher and it gets foggy above the water.
  • Former Member
    Former Member over 16 years ago
    Anyone knows how public swimming pools are maintained? Do they completely change the pool water at the end of day, or weekly? Anything they do to the pool overnight (just circulate like daytime, or do nothing, or change entire pool water)? Is the water cleaner in early morning than evening because of this? Thanks. I think our Y is every other year.
  • Former Member
    Former Member over 16 years ago
    Most pools, I think, are only drained completely once or twice a year. Pools I've worked at have crews come in and night and vaccuum the entire pool, or the lifeguards put in an automated little robot who does it. It kind of depends on if the pool is indoor or outdoor and what it's used for. Chemicals (chlorine levels, etc) are always checked at least twice a day though in any pool regardless of location or primary function. I'd say the pool is the same amount of clean all day. Maybe a little more so in the morning simply because people haven't been in it for a few hours.
  • Former Member
    Former Member over 16 years ago
    I moved to Colorado from Houston 10 years ago and was amazed that they drain pools in Colorado...ever. I was a swimmer and lifeguard in Houston for over a decade and I don't remember anyone ever draining a pool except for major maintenance. It certainly wasn't routine. I could be wrong, but I think you could theoretically maintain a pool without draining it forever if you had the right chemical balance, filtration, and debris removal. I believe good filtration systems filter the entire volume of a pool every couple of hours. Every pool needs "fresh" water to replace what evaporates or is splashed out. I would contend that most pools are about the cleanest place you'll subject yourself to in a given day (consider what's on a bathroom doorknob), if we're talking about germs. It always cracks me up when they close a gigantic pool for 24 hours because some kid puked or had an accident. With the chlorine and pH levels in most pools, I don't believe there is any real danger after a few minutes, especially when they scoop some more chlorine in the affected area. From a former lifeguard's perspective, we always loved it when that happened because we got out of work for the day.
  • Former Member
    Former Member over 16 years ago
    Typically, pools are not drained completely unless there are major renovations or maintenance demands. There simply is no need to do that. Fresh water is added to the pools - either manually or through an auto-fill system - either directly into the pool or in the pump room. Water is loosed through evaporation, pool activities and routine cleaning of the filtration system (backwashing). Occasionally, fresh water will need to be added (after pool water is "dumped") because of an extreme chemical imbalance. In this case, the pool should be closed and you probably will not know about it. There is a number of reasons pool water turns "white cloudy" (low turbidity). Improper filtration, insufficient water circulation or flow rate, poor water chemistry, wind, rain, vegetation, dry skin flakes, cosmetics and hair products from swimmers are among the many factors that need to be examined. In short, cloudy water is the result of microscopic suspended particles. Determining the contributing factor will yield the proper remedy. If the pool water turn colors like blue-green or red-brown, then you have a more serious condition and should have an expert examine the situation. Pool water temps. in relation to air temp.: The most ideal is to have the air temp 5 degrees warmer than the water. This is not always possible. At a minimum, air flow/ventilation is absolutely necessary. Recreational water illnesses are caused by cryptosporidium (parasite), Giardia (parasite), E. coli (bacteria) and shigella. When people infected with these diseases have a fecal release in the water and there is insufficient disinfectant (most often Cl) to inactivate the pathogen, then swimmers who ingest water, will swallow some of those germs and will become ill. Crypto can remain active at normal disinfectant levels for several days (6 -7 days). Protozoa are resistant to chlorination in swimming pool water. Therefore, remedies for total disinfection are to raise the Cl (or sanitizer) level to an unsafe swimming level and allow the pool water to turn over (filter) and return to an accepted level. The flow rate (turnover rate) at your pool will determine the length of time this process will take. In most areas, at a minimum, the Health Department regulates pools by taking weekly water samples and yearly visits. If there is a problem cited or water tests reveal a potential hazard, the Health Department is obligated to intervene and possibly fine ($$) or close a pool until the problem(s) are resolved. that's my :2cents: -mermaid- CPO PA Dept. of Agriculture, Certified Commercial Pesticide Applicator Registered Public Bathing Place Manager
  • Former Member
    Former Member over 16 years ago
    Thanks to the replies! That is so informative! I had thought they drain the pool every day, or at least every week! How laughable! Though in theory one could catch disease from a public pool, I haven't heard of real instance yet, so maybe most pool are ok... Whatever, we have no choice...
  • Former Member
    Former Member over 16 years ago
    I lifeguarded and maintained pools for about six years beginning in high school and through most of college. I worked at community pools, a country club pool, and several pools at an Air Force base in San Antonio. We never drained the pools. Water wasn't expensive then but it is now. In my experience water quality was always best in the morning unless circulation was turned off overnight. I haven't been in a "public" pool that had filtration to keep a pool crystal clear throughout a day when people were in it. But overnight the filters catch everything because nothing new is being introduced into the pool. People bring dirt into pools. Sweat, skin flakes, suntan oil, etc. Chlorine breaks down in the sun - so chorine use is much higher during the day for an outdoor pool. We occasionally forgot to turn the chlorine down (when we had a chlorinator) at the end of the day. The result was very high chlorine levels in the morning. Chlorine doesn't work as well when the ph is wrong - so the chemical balance is important. Filters also need to be cleaned or backwashed (reverse the direction of water flow to rinse dirt out of the filter media (like sand). Algae grows too - and is usually taken care of with more chlorine. The algae is killed, but needs to be physically removed from the pool via vacuum or the filters (not effective because the dead algae settles on the bottom). I don't think there is any excuse for frequently cloudy water. Pools will not be crystal clear all the time but the water should be appealing most of the time.
  • One thing they do in Europe that we don't have in the US is walking through a foot-pool before going on deck. I have to image that simple step (especially after visiting the rest room!) would help keep the water clean. (Too bad the heavy perfume/cologne people forget about the "take a shower before entering the pool".)