When rainwater and 'run off' enter the pool, they can change your water's pH, calcium hardness, total dissolved solids (TDS), alkalinity, and other chemical levels as well as bring contaminants such as dirt and debris into the pool.
The Department of Environmental Health recommends avoiding activities such as swimming, surfing, and diving for 72 hours after it rains. Research has shown that the risk of infection is the highest during and the day after rain, and declines to around normal levels after three days.
Shocking your pool isn't necessary, although, it's not a bad idea either. If you get an extremely heavy rain fall, you could shock your pool for good measure. This will help fight off any contaminants that the rain may have brought to your pool.
If your pool is completely full after a storm or heavy rainfall, you don't need to take drastic steps such as emptying your pool. If you do, the hydrostatic pressure can cause your pool to come out of the ground.
It is recommended to wait at least 20 minutes to an hour after adding water balancing chemicals. You should wait 2-4 hours (or one full cycle through the filter) to swim from the moment you use calcium chloride in your pool. It is safe to swim once your chlorine levels are around 5 ppm or after 24 hours.
Before getting in
Don't swim or let others swim if sick with diarrhea. Shower for at least 1 minute before you get into the water to remove dirt or anything else on your body.
Having too much chlorine in your pool water can be dangerous. Exposure to high levels of chlorine can cause lung irritation, skin and eye damage, and provoke asthma. Not only is it bad for your health, but it can be bad for your pool due to the increase in chlorine.
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.
It is important to know what exactly bleach is before you put it in your pool. Household bleach, Clorox and liquid chlorine can all be used to sanitize a pool. They are all types of chlorine. Household bleaches such as Clorox usually contain about 5-6% available chlorine, about half that of pool liquid chlorine.
Chlorine reactions may include itchy, red skin or hives (itchy bumps). This is not an allergy but is actually “irritant dermatitis” (like a chemical burn), caused by hypersensitivity to this natural irritant. Chlorine is also drying to the skin and can irritate existing dermatitis.
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.
What chlorine level is too high to swim? It depends on who you ask, but the acceptable range is between 1 to 5 ppm. (So, for example, 10 ppm chlorine is not safe to swim in — that's too high.)
Although swallowing a small amount of pool water is harmless, it's important for parents to realize that ingesting too much can lead to chlorine poisoning or so-called recreational water illness, according to Dr. Sampson Davis, an emergency room physician at Meadowlands Hospital Medical Center in New Jersey.
You should never swim alone, always swim with a "buddy". And keep an eye on each other, even at a guarded pool or beach. And parents, keep an eye on young children even when they are with another person and a lifeguard is present. False.
The best way to determine if a body of water is safe and the risk of water borne illness is low is to sample the water and check for Escherichia coli (E. coli) bacteria. E. coli is commonly found in the intestines of humans and other mammals.
The Bottom Line about Pools and Chlorine
As mentioned above, you could probably swim in a pool without chlorine without any major health issues. However, long-term use of a pool lacking chlorinated H2O could make you sick or, at the very least, contribute to rashes and other types of skin irritation.
Swimming pool builders often install overflow drains near the rim of the pool that prevent flooding most of the time. If you don't have an overflow drain, or if it is clogged, it is possible for periods of unusually heavy rain to overflow your pool.
Too much rain can raise the water level in your pool to overflowing if you're not careful. If the water in your pool is in danger of overflow, you may need to drain the pool. There are numerous how-to videos online that go over this process.
The first choice for draining swimming pool water should be to drain pool water into the sanitary sewer. In-ground pools typically have a sanitary sewer drainage inlet near the pool equipment. Pools and spas not plumbed with a sanitary sewer drainage inlet can be drained to a sanitary sewer line plumbed to the home.
At the first sign of an incoming storm, you should turn off and unplug your pump. If this is left running during a storm, the motor may suffer electrical damage and short out.