Private well water might look like other types of water from public systems, but it contains a different set of dissolved substances that affect how a swimming pool functions.
Common groundwater contaminants that exist in most types of well water can cause clouding, discoloration, pH imbalances, and clogging of pool components if not correctly treated.
With the proper steps taken, however, you can absolutely use well water to fill swimming pools or hot tubs. Done correctly, you may even save money over other options like having your pool water pre-treated and delivered.
Here are 3 do’s and 3 don’ts when filtering well water for swimming pools.
Overestimate your well capacity
One of the first things to think about when filtering well water for pools is the overall capacity of your well. Many domestic wells have low flow rates, under 4 gallons per minute, which might be sufficient to run your home, but may not be enough to fill a swimming pool at the same time.
The thing to remember here is that flow rate is not just a measure of how fast water flows from a well, but also an indication of how quickly a well refills. If water demand exceeds a well’s flow rate for an extended period, then you risk the well running dry.
Letting a well run dry can cause issues with sediment accumulation, where the well pump starts to bring up sand and silt. This can cause clogging throughout your plumbing, and may result in the need for a professional well service. Pulling high amounts of water from a well may also deplete the surrounding water table and supply of neighboring wells.
If you’re lucky enough to own a domestic well with a GPM of around 10 or more, then you should be able to use it to fill a swimming pool (or for other high water demand activities). Lower GPM wells may still work, but in that case, it’s better to fill the pool slowly, over the course of a few days.
Use one filtration system for both your home and swimming pool
There are several stages in well water filtration systems, which means that water slows down as it passes through the system on its water to your faucet. While good filter systems only have a small effect on water flow, they’re not usually designed to handle the amount of water needed for both a swimming pool and a house.
Instead, you’ll need a separate filter system specifically for your pool water. Install the filter between your well and swimming pool to prevent it from affecting water flow to your house.
Just like a home filtration system, you’ll want to make sure your swimming pool filter has the right stages for your needs. These may include a softener to take care of hard minerals, and a sediment filter to clear sand and dirt from the water supply.
Often, the best type of filter for a swimming pool is a reverse osmosis filter. Many experts don’t recommend reverse osmosis filters when it comes to well water in homes, as they can restrict the flow rate too much. But for a pool, that’s less of a concern, and reverse osmosis filters will remove dissolved solids, harmful substances, and any bacteria.
If you do use a reverse osmosis filter, you’ll also need a good sediment filter to avoid clogging the fine osmosis membranes.
Rule out pool water delivery
If you think that your well capacity or the concentration of contaminants in your well water will make filling your swimming pool difficult, don’t rule out using a water delivery company. These services deliver pre-chlorinated potable water to property, specifically formulated for pools and hot tubs.
Using a water delivery service is obviously more expensive than filling a pool from your own well, but it comes with some clear benefits. Most importantly, there’s no need to fight against high levels of iron and hard water minerals, which means savings on filtering costs and less stress on pool components.
After all, nobody wants to swim in yellow or brown water, which is what can happen if you’re unable to sufficiently reduce iron and manganese levels.
Filter for minerals and metals
Iron, calcium, manganese, and other metals and minerals are all highly common in well water, which is bad news for swimming pools.
Substances like calcium and magnesium create hard water, which creates scale when it spends long periods in contact with surfaces. Most swimming pools have lots of filter piping, which can become easily clogged with mineral deposits if water isn’t softened and/or filtered.
When water contains lots of manganese and/or iron, swimming pools can take on a brown or green tinge that looks highly unwelcoming. An excess of iron also increases the risk of bacterial contamination, as several common types of bacteria thrive in iron-rich environments.
Sand filters and softeners are common devices used to reduce mineral levels in pool water.
Correct imbalanced pH levels
These groundwater contaminants can also contribute to an imbalanced pH level in water. If pool water is too acidic or alkaline, then it may become discolored and cause irritation to skin and eyes.
Acidic pool water (with a pH level below 7.0) can be easily felt by swimmers, especially around the eyes where it causes itching and discomfort. The more acidic water becomes, the higher the likelihood of damage to your pool components, including corrosion of any metallic parts. pH basicity correctors like soda ash can be used to balance acidic water.
Alkaline pool water (with a pH level above 7.0) should be avoided because it can make chlorine a less-effective disinfectant. This raises the risk of unsafe contamination. Like highly acidic water, highly alkaline water can also result in swimmers encountering rashes and skin irritation. pH basicity correctors like muriatic acid help lower alkalinity.
Even though correctly filtered well water should be free of bacteria, viruses, and other microorganisms, you’ll still need to periodically disinfect your pool with chlorine.
“Shock chlorination” is the term often used for periodic chlorine disinfection, where large amounts of cleaning chemicals ( too high to swim in), are cycled through the entire pool system to get rid of any growing bacteria or microscopic plant life.