Is it OK to Use Well Water to Fill a Pool?

Filling a swimming pool is damn expensive man, and it makes sense to use alternative water sources to fill your pool. In some places, the ONLY water source is a well. So, is it okay to use well water to fill a pool?

Using well water to fill your swimming pool is perfectly fine, and can save you a ton of cash. There are some things to consider though, such as metal content, residue, and funny smells, but these can be fixed with some basic extra chlorine, filtration, and a bit of time.

High Metal Content of the Well Water

You will want to remove unwanted minerals such as iron from the water. If the water turns brown when you add chlorine, you have high iron levels. High iron levels will stain the finish or liner of the pool.

How to remove iron from the water:
Use a flocculant to bind the iron into clumps. These clumps will collect at the bottom of your pool as a residue that you can simple vacuum up. Be sure to run the pump on “backwash” mode while you vacuum. Also, do not allow your pump to run while there is flocculant in the water, as you don’t want this stuff in your filter.

Here’s an in-depth article I wrote on how to remove iron from your pool water: How to Get Rid of Brown Pool Water

How to remove Mengenese from the water:
Manganese can be present in water from very deep wells. This can cause purple coloration in your pool water and dark purple stains on the pool walls.

Manganese can be removed in the same way that iron is removed using a flocculant.

Calcium Hardness of the well water

Water will high calcium hardness levels is called “hard water”. Hard water is not good for your pool equipment and pool surface.

Hard water will also appear cloudy which does not look that great.

Ideal calcium levels should be between 175 and 225 ppm if you have a vinyl or fiberglass pool liner and between 200 and 275 if your pool has a concrete or plaster lining.

How do I know if my water is too hard?

  • Cloudy water is usually the first sign of hard water. If a shock treatment does not clear the cloudiness, then it is likely that your water is too hard and contains too much calcium.
  • Calcium buildup will appear on the surfaces of your pool.
  • Calcium Hardness Test will quickly tell you if your water is too hard.

How do I lower the calcium hardness of my pool water?

  • Pool Flocculant will cause the calcium to clump up and gather at the bottom of the pool. Turn off your pool pump before adding flocculant. You can then vacuum up this residue, and make sure you vacuum while the pump valve is set to waste.
  • Add Muriatic Acid. This won’t lower your calcium hardness level, but it ill raise your saturation level, bringing your pool back into balance.

You can avoid most of the metal content-based problems by simply running the well water through the filter before dumping it into your pool.

Don’t dry up your well or burn out the well pump!

Filling your pool with well water will take some time. You need to be patient. Make sure you don’t rush it and pump the water all in one go.

Pump the water in short shifts spaced over a few days. This will ease the strain on your well pump and also give your well a chance to refill. It is quite possible to drain your well stone dry.

What’s that smell? Rotten eggs? Nope…

The water from the well might smell like rotten eggs thanks to hydrogen sulfide. While hydrogen sulfide is harmless and even drinkable, it makes swimming very unpleasant, and hydrogen sulfide can also corrode metal fittings in your pool.

How to get rid of that rotten egg smell in my pool water?
Try to triple shock your pool, by adding 3 pounds of chlorine for every 10,000 gallons of water. This will oxidize the hydrogen sulfide to sulfur or sulfate, and the smell will start to go away. Once this is done you will have to filter out through the filter of your pool. Be sure to backwash often during this filtration process.


Filling your pool with well water is perfectly fine. Most of the time, water from a well is drinkable and certainly safe to swim in. Unless you get very lucky with your well water though, you will need to treat the water for high metal content and that infamous rotten egg smell.

Most of the time, well water will have high iron and manganese levels. You can use a flocculant to bind the iron and manganese into clumps that you can then vacuum up and send it to waste-water.

Iron and manganese are harmless to swim in but can be very damaging to pool equipment. They will also tint your water brown (iron) or purple (Manganese) once you have added chlorine. So it is worth taking care of.

Well water will almost certainly have a high calcium hardness. This will be determined by cloudiness in the water, as well as a build-up of residue on the surfaces of your pool. You can also use a test if you are still not sure about the calcium hardness of the water.

You can use a pool flocculant in the same way as you used to get rid of high iron and manganese levels to treat high calcium hardness. Failing that, you could also add muriatic acid which will raise the saturation of the water, balancing the water.

It is also wise to take your time when you are filling up your pool so that you don’t overwork and damage your well pump. It is also possible to run your well dry by rushing this process. Break the task up into short shifts spread out over a few days.

Lastly, and most ghastly, you might notice a rotten egg smell in the water. Don’t freak-out! This is quite normal and is easy to fix.

Simply triple shock your pool, this will oxidize the hydrogen sulfide, removing that terrible smell. This will leave sulfur or sulfate that will gradually be removed by your pool filter.

PS: Why did the blind man fall down the well? He couldn’t see that well

Leave a Reply

Your email address will not be published. Required fields are marked *