Pros And Cons To Filling A Pool With Well Water

Pool Well Water Quick Answers:

  1. Is It OK to Fill a Pool with Well Water?
  2. Filling a Pool with Well Water: What to Consider
  3. Test Before You Fill
  4. It’s All About Balance
  5. How to Fill a Pool with Well Water
  6. Treating Well Water for a Pool
  7. Consider Your Equipment
  8. Can You Have Water Delivered to Fill a Pool?
  9. Balance Your Water with Pool Calculator

There’s one extremely simple question every swimming pool owner must answer: Where will the water come from?

If you’re like a lot of pool owners, you might be wondering if it’s safe to fill a pool with well water. The short answer is yes, you can – but there are some important things to consider before you proceed. 

In this article, we’ll explore what you need to know about using well water for your swimming pool – including how to know if your well can supply enough water, what to test for, and about the proper pool maintenance.

Is It OK to Fill a Pool with Well Water?

a brick well with a silver bucket surrounded by bright green grass on a sunny day
It isn’t that common to have a well close to your house, but if you do, make sure you check your town laws before taking the well water. You can also get well water delivered to your home.

As we said above, you can fill your swimming pool or hot tub with well water. In fact, it’s one of the least expensive options, especially compared to a pool water delivery service.

Some people choose to fill their pools with city water or municipal water from their house, but not everyone has this option. If you have your own well or access to one near your home, making sure it has a sufficient supply of water is crucial. (More on that shortly.) You’ll also need to test the water before using it in your pool, and you may have to treat it once it’s full. 

Filling a Pool with Well Water: What to Consider

Can a well provide enough water for your pool? This depends on the size of your pool and the well’s supply. The well’s flow rate (or delivery volume) is the number of gallons of water it can produce per hour – which actually represents how quickly water flows back into the well[4]. In other words, a well can’t expel more water than it takes in.

Around 600 gallons per hour would be considered a high flow rate, and anything lower than about 150 gallons per hour would be low. If it has a high flow rate, the well can most likely fill a pool, but with a low flow rate, it may run dry. You should also consider whether you’re sharing the water table with neighbors and whether you’re currently in a drought.

Most wells are drilled deep into the ground, which makes the water less likely to be contaminated with bacteria, viruses, and human waste. However, since it sits below ground level for a relatively long time, there’s a good chance the water contains various minerals and trace metals. These can include:

  • Arsenic
  • Calcium
  • Chromium
  • Cobalt
  • Copper
  • Iron
  • Lithium
  • Magnesium
  • Manganese
  • Molybdenum
  • Nickel
  • Selenium
  • Vanadium
  • Zinc

When it comes to swimming pools, the presence of these contaminants can create some issues[1]. For example, calcium hardness (or hard water) can lead to clogged filters and pipes. 

Additionally, when water contains too much manganese or iron, it can lead to bacteria growth. In some instances, high levels of iron can visibly tint the water a brownish-green color and stain the walls of a pool or swimmers’ hair.

Test Before You Fill

Before filling up your pool from a well, you should test the water to check if there are heavy metals, or high levels of minerals, bacteria, and other contaminants. This will give you an idea of how to treat it and whether your filter will be able to effectively clean it. We suggest using test strips, which will provide you with the most accurate read.

A water test will tell you whether your well contains high amounts of iron or manganese. If the levels are too high, you may want to consider treating the water in bypass before filling your pool. Balancing the water chemistry can take time, but will help you avoid discoloration and bacteria growth, as well as prevent filter damage.

It’s All About Balance

The presence of metals and minerals can impact the alkalinity and pH levels of water. For this reason, it’s important to be aware of chemical imbalances if you’re planning to fill your pool with well water.

A chemically balanced pool is a clean and crystal-clear pool. The good news is that you can balance water chemistry by carefully treating it. However, it can be a somewhat difficult process and may take a little time to get it right.

When you test the water, you might find that the pH is either too low or too high, in which case it will need to be balanced with a chemical treatment. If it’s too high, you’ll need to treat it with a pH- basicity corrector. If it’s too low, you’ll treat it with a pH+ basicity corrector.

How to Fill a Pool with Well Water

Even if your well has a high flow rate, we recommend filling your swimming pool slowly over the course of a day or two – or longer if you’re filling an extra-large pool. 

Your household may have plenty of water and a high flow rate on a day-to-day basis, but it may not be able to handle the additional demand of filling an entire swimming pool. Also, some wells are shared by multiple households, so you’ll want to make sure you aren’t impacting your neighbors’ water supply. Filling your pool slowly over the course of a few days will help mitigate this potentially serious issue.

Start by running the water at half its potential speed for about an hour. Then stop the water for another hour to allow it to replenish itself. Continue filling the pool for one hour at a time, followed by an hour off, until it’s full.

a hose filling an inground pool with water
Make sure you don’t fill the pool all at once and that you fill it in hour increments. 

Treating Well Water for a Pool

Testing the water will give you an idea of which pool chemicals you should treat it with. As we mentioned, if your well water has a substantial amount of iron or manganese, you may want to treat it with chlorine and algaecide in bypass before filling your swimming pool. A sequestering agent can be used to treat hard water and remove trace metals.

You may also need to treat your well water with a pH+ or pH- basicity corrector and cyanuric acid, which stabilizes free chlorine levels in outdoor pools. Another treatment option is pool clarifier, which collects tiny particles and combines them into larger pieces that can be scooped or filtered out.

a pool test kit with yellow and pink colored solution and two test tubes inside of a blue box
This is an extremely common type of pool test kit that you may find at the store. 

Another important treatment is chlorine shock – an all-purpose pool treatment that removes bacteria, algae, and contaminants. A natural swimming pool can be treated with chlorine shock as well. Bear in mind that chemical treatments can take a few days to work, and UV exposure can impact the effectiveness of chlorine. That said, cyanuric acid will help protect the chlorine from the sun’s UV rays.

Additionally, chlorine shock can be used for pool maintenance by helping you avoid recurrent contamination. To maintain clarity and healthy chemical balance, it’s also important to have a functioning filtration system and use disinfectants[2].

Consider Your Equipment

Before filling your pool with well water, you should consider how it may affect your equipment. Since well water contains more metals and ions than city water, it requires your pumps, filters, hydraulics, and pipes to work much harder[2]. As a result, your pool pump and filtration system might wear down sooner than they would with water from a delivery service or municipal water.

It’s possible you’ll need to replace your equipment more often with well water. Your pool liner may need to be replaced sooner as well if the water contains high levels of manganese and iron. You’ll have to crunch the numbers to see which option is best for filling your swimming pool.

Can You Have Water Delivered to Fill a Pool?

If you decide against using well water to fill your pool, another option is a bulk water delivery service. This would mean having a truck deliver enough potable or pre-chlorinated water to fill your pool. Prices vary for pool water delivery, so you’ll have to check what’s available in your area to decide whether it’s a financially suitable option for you.

Balance Your Water with Pool Calculator

Regardless of how you fill your pool, it’s absolutely essential to test and balance your water chemistry frequently. That’s where Pool Calculator comes in. We make it simple and seamless to keep your pool clear, clean, and balanced. With our convenient app, you can test your chemical ranges, find your total alkalinity, balance your pH, stabilize your free chlorine levels, and check for calcium hardness. Get the Pool Calculator app on your desktop, Android, or iOS mobile device to get started!

External sources:

1. https://www.epa.gov/privatewells/potential-well-water-contaminants-and-their-impacts

2. https://www.who.int/water_sanitation_health/bathing/srwe2full.pdf4. https://inspectapedia.com/water/Well_Flow_Rate.php

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