Can You Fill a Pool with Well Water? What You Need to Know

If you have a backyard pool, using well water to refill it seems like an easy decision. It is there, it is free, it is easy. So, can you fill a pool with well water? The answer is usually yes, but you will want to make sure that the water quality, availability, and well capabilities are a good fit for the task.

Reasons to Fill a Pool With Well Water

Why would you fill a swimming pool with well water? There are a few good reasons:

• It is inexpensive, if not free. The electricity to your well pump may be the only cost.

• Well water is often plentiful, convenient, and easily available.

• Well water is almost always free of chemicals. (Public water supplies can contain chlorine and other chemicals that affect the pH and quality of pool water.)

Reasons Not to Fill a Pool With Well Water

Before you get out the hose, learn the downsides of filling a pool with well water. Some of these may apply to you:

• Well water is untreated by a public water treatment facility, so it can contain bacteria or contaminants.

• It may contain minerals and trace metals that can pollute a pool or harm equipment.

• Large pools can take a long time to fill, especially if the well refill rate is slow.

• Drawing too much water can strain water supplies, compromise a water table or aquifer, affect neighboring wells, and cause wells to run dry.

• You can burn out the well pump.

Factors to Consider

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Filling your pool with well water is not quite as simple as hooking up a hose and opening the spigot. First, you need to determine whether you can safely use well water in your home pool. Here are some things to consider.

Pool Size

If you have a smaller-sized pool, using well water may be a good choice. But if you have a large pool and your well does not produce water quickly, it can take days or weeks to generate enough water. 

Worse yet, if your pool is very large or your well is not deep, you can risk the well going dry during the process. Along with a temporary lack of water, this can cause even bigger problems, including needing to drill a new and deeper well.

For these reasons, you should know the size and capacity of your pool before filling. This will help you to gauge whether your well system is adequate for refilling the pool, and it can help you estimate the cost to fill your pool with water, should you opt to buy water elsewhere. If you do not know the size and capacity of your pool, talk to a local pool installer near you. You can also use a pool volume calculator to estimate the size.

Water Availability

Groundwater is not limitless. Your well is likely fed by an underground aquifer, and aquifers can run slowly and even run dry. If you share a well with neighbors on the same water table, if your area has been experiencing drought or low-water conditions, or if there are other factors impacting local water availability, pulling water from a well can negatively impact you and your neighbors.

Before filling a pool with well water, you need to know how much water is available and whether there are any supply-and-demand issues that may impact the process. You do not want to find yourself without sufficient water for your home and garden.

Water Flow Rate

How fast water flows from your well will dictate how quickly you can fill a pool. The well flow rate, also called delivery volume, is how many gallons per hour your well can produce. This is also how fast your well refills, because wells cannot put out more water than they take in. A flow rate of 600 gallons per hour is considered a high flow rate; 150 gallons per hour or less is a low flow rate.

Why is it important to know this? You can usually fill a pool if your well has a high flow rate, even if it takes a while. But wells with low flow rates can run very slowly and even run dry temporarily. Low-flow wells that are stressed can also pull up dirt, minerals, trace metals, and sediment that can make your water (and pool) dirty.

Pump Effectiveness

Your well has a pump that brings water to the surface. If that pump is older, slower, clogs easily, or has other problems, it will not bring water up fast enough and it can take a long time to refill a pool. You also risk burning out your pump, and they can be expensive to replace. For these reasons, you will want to make sure the well pump is up to the task.

Water Contaminants

Well water in pools is safe for the most part. If your well is drilled deeply enough, the water should be safe from bacteria, viruses, farm runoff, and septic runoff; however, well water often contains trace minerals and metals. Too many of these and you risk damaging the pool, clogging filters and pipes, growing bacteria, and swimming in discolored water.

Environmental Impact

Water use is a hot topic in many areas, and refilling a pool takes a lot of water, regardless of where you get it. It is good to think about where water comes from and ways to limit your environmental impact while still enjoying your pool. Knowing which water sources and refilling methods have a lower impact can allow you to make decisions that align with your priorities and sense of fun.

How to Fill a Swimming Pool With Well Water

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If you have decided to fill your pool with water from a private well, test the water first. If bacteria, minerals, or other contaminants are present, treat the water before using it or get water from another source. You should also check the well flow rate to ensure it can supply water fast enough. Once you have the all-clear, here is how to proceed:

• Plan to fill your pool slowly over a day or two or more.

• Attach a clean garden hose to an outdoor spigot near your pool. Attach a hose filter.

• Place the hose in the pool. Place it in the pool filter basket for added filtration. You may need to anchor it down to prevent spills and waste.

• Turn on the water at half the maximum flow for an hour.

• Stop the water and allow the well to refill for an hour before turning the water on again.

• Monitor the water for slowing, color change, or other indicators that the well refill rate cannot keep up. If you notice these issues, turn off the water for a few hours. When you start filling again, turn the water on to one-quarter the maximum flow. If problems persist, stop filling.

• Follow this pattern until your pool is full.

• Test and treat the water during filling and before swimming. Depending on the water quality and your preferences, you may need to treat it with some combination of chlorine shock, chlorine or bromine, algaecide, a sequestering agent for hard water and metals, pH corrector, and pool clarifier.

• Have regular pool inspections done to ensure your systems and equipment are working properly and that your well water is not causing harm.

Where Else to Get Pool Water

If well water is not a good match due to mineral content, scarcity, or other concerns, where else can you get pool water? Fortunately, there are a few other sources.

Municipal Water Sources

Municipal water comes from a public water treatment facility; it is what runs to most homes located in cities that are connected to public water supplies. Like any option, municipal water has pros and cons. 

Pros

• Readily available

• May have a lower environmental impact because it can be treated or comes from recycled water that does not draw from groundwater supplies

• Often higher quality than well water

• Generally free of contaminants, such as minerals and trace metals

Cons

• Can be expensive

• May contain chlorine and other treatment chemicals, which can cause problems with pool pH levels

Tip: In certain locations, water companies may waive some water use charges for customers who are filling a pool if you call ahead. If you plan to use city water to fill a pool, call the local water utility before starting and ask if they will eliminate sewage charges or offer other discounts.

Pool Water Delivery Services

Depending on where you live, you may be able to hire a pool water delivery service to bring water to your home. This can include municipal water, potable water meant for drinking, and even pre-chlorinated water.

Pros

• Easy and convenient

• A smart choice for homeowners with slow-flowing wells or low water supplies

• Water can be pre-chlorinated.

Cons

• More expensive than well water and municipal water supplies

• Can be hard to find in some locations

• You should still test the water upon arrival; you may need to treat it to balance the chemicals.

Lakes, Rivers, and Other Natural Sources

Some homeowners live near lakes, ponds, rivers, creeks, and other sources of natural water, and it can be tempting to find a way to use this water to fill a pool. This can be dangerous, though. Most experts will tell you not to use pond, river, or lake water in all types of pools and spas for safety and cleanliness reasons. Here is more to consider; as you can see, the cons outweigh the pros.

Pros

• Free (minus the cost of the pump and electricity)

• Water may be plentiful and easily available.

• Once you invest in a pump, filter, and other supplies, future fills will be easier.

Cons

• Natural water can be very dirty and require filtration.

• It often has organic material, algae, bacteria, viruses, chemical and fertilizer runoff from fields and yards, minerals, and other things you do not want in a pool.

• It will require testing at the source and in the pool to ensure safety.

• You can become sick or get infections from improperly treated water.

• It can deposit organic material and algae in your pool, making it dirtier and harder to keep clean.

• Organic materials and minerals can clog pool filters and equipment.

How to Avoid Water Loss

No one wants to refill their swimming pool more often than they have to, and the best way to prevent frequent refills is to prevent water loss in the first place. In fact, according to the Department of Energy, evaporation causes up to 70% of water loss from pools. Your pool can lose up to a quarter-inch in depth each day. Here are some tips for keeping water in your pool.

• Identify and fix leaks.

• Use a pool cover, such as a solid cover or solar blanket.

• Try a liquid solar blanket. This microscopic film covers your pool surface with a protective molecular barrier that slows evaporation.

• Turn off water features when you are not using the pool.

• Lower the water temperature.

• Avoid excess splashing and too-frequent cannonballs.

• Do not overfill your pool. If the water level is too high, it is much easier to splash out excess water.

• Install a windbreak with landscaping, fencing, or custom options.