I think the answer to your question is about 3-6 days. The problem is that the chlorine that you need to keep the bacteria in check is used up more quickly as the temperature rises, the activity increases, and as sweat and other body stuff is put into the pool.
It takes a lot of chemicals to make pool water safe for swimming. Untreated water can accumulate harmful Escherichia coli and Salmonella bacteria and protozoans such as Cryptosporidium parvum and Giardia lamblia.
Maintenance is critical when it comes to the quality of your pool water. Well maintained pool water can last up to 5, maybe even seven years before you need to replace it. This means weekly cleaning, functional filters, and checking ph levels every day. Usage is a huge determining factor.
A pool can only be safe for swimming without a pump for a few days and a maximum of one week. The definite number of days the pool will be safe will also depend on the temperatures of the water, the weather at that particular time, the level of chlorine, and how clean the pool was before the pump stopped functioning.
If you'll only be adding liquid chlorine, it's generally safe to swim after about 4 hours or until levels are 5 ppm or lower.
So if you have to rely on your pool, the only sure way to make the water safe for consumption is to filter and distill it. Filtering gets the big stuff out and even many chemicals (if you're using a carbon-based filter) and distilling it will remove everything else.
Chlorine, either solid or liquid, is a pesticide used in pools to destroy germs, including those from feces, urine, saliva and other substances. But excessive exposure to chlorine can cause sickness and injuries, including rashes, coughing, nose or throat pain, eye irritation and bouts of asthma, health experts warn.
Pool pumps typically disperse chlorine into the water for you, but it is possible to add chlorine without a pump. The easiest way to do this is with chlorine tablets. They go in a designated floating container and slowly dissolve while floating around the pool. You can also use inline chlorinators.
Stagnant, still water is a breeding ground for gunk. Keeping your pool clean requires keeping the water moving and circulating. If you still have electricity, you can use a robotic pool cleaner or a submersible pump to clean, move and circulate the water. If you are without power, grab your pool brush!
Shock is liquid or granular chlorine. You should add one gallon (or one pound) of shock per 10,000 gallons of pool water every week to two weeks. During hot weather or frequent use, you may need to shock more frequently.
Flooding Your Grass Is Not A Good Idea
The problem with draining your pool in the yard, if permitted by your local water regulatory laws, is that it will quickly reach its saturation level and increase the risk of flooding your lawn, drowning the roots of your grass, and attracting mosquitoes.
“It's important to change the paddling pool water every day – drain it and let it dry at the end of the day and use an anti-bacterial spray to kill any germs so it is safe to use the next day.”
Pool water cannot be used to water plants unless the chlorine content is reduced. Chlorine eliminates bacteria and algae in pool water by disinfecting or killing action. It also oxidizes other materials such as dirt and chloramines and can harm plants in high quantities.
Short answer--yes. The first response, however, would be why would you use a pool without a filter? The sand filter or other filtration system is essential to the health and safety of the swimmers. It is also necessary to have a circulation pump for maximum chlorination.
To keep the pool clean without a filter, it is necessary to use chlorine with a flocculant or to use a flocculant chemical. This product groups the impurities that float in the water, causing them to fall to the bottom of the pool so that they can be removed later with a cleaner.
BUT, if you have to shock your pool during the day in broad daylight, you can still swim after adding shock. It's recommended that you wait one hour after adding shock with the filter running, and then test the water to confirm the pH and chlorine are in the proper range before letting anyone enter the pool.
After Shocking Your Pool
It is safe to swim once your chlorine levels are around 5 ppm or after 24 hours. It is always best to test first!
When opening your pool in the spring – When a pool is first opened, the chlorine level normally needs an immediate boost, and shock is the quickest and easiest way to accomplish this. If the chlorine level is already adquate, a non-chlorine shock may be used to treat the water.
Regardless of how frequently or what system you use to add chlorine to the water, the chlorine level should stay between 1.0 and 3.0 parts per million (ppm) to maintain a healthy pool. Anything higher will make you to run the risk of red eyes and swimmers itch.