Filling a Pool With Well Water in the Hill Country: Stains, Scale, and Fixes
Many homes in Spring Branch, Canyon Lake, Bulverde, and Wimberley get water from a private well. Well water can work fine in a pool, but it often brings two problems: very hard water and metals. Here is what to watch for and how to fix it.
Problem 1: Very Hard Water
Hill Country wells pull water from limestone, so it is often very hard. Hard water leaves white scale on tile and inside heaters and salt cells. Test calcium hardness every week and keep pH and alkalinity in range. See tile and calcium removal.
Problem 2: Metals Like Iron
Some well water carries iron, manganese, or copper. You may not see it at first. But when you add chlorine, the metal can come out of the water and show up as color.
- Brown, rust, or orange water after shock often means iron.
- Purple, black, or dark stains can mean manganese.
- Blue-green stains can mean copper.
How to Fill a Pool With Well Water the Right Way
- Test the fill water for metals before filling.
- If metals are high, use a hose-end pre-filter while filling.
- Add a metal sequestrant before you shock.
- Balance pH and alkalinity before adding a big dose of chlorine.
- Run the filter well, and clean it after metals are caught.
Fixing Metal Stains
Many metal stains can be lifted with the right stain treatment and then held in the water with a sequestrant. Stains that will not lift may need an acid wash. A water test is the first step, so you treat the right metal.
Salt Water Pools on Well Water
Hard well water builds scale on salt cells faster. Check and clean the cell more often. See salt water pool service.
Frequently Asked Questions
Can I fill my pool with well water?
Yes, but test it first. Well water in the Hill Country is often very hard and may carry metals that can stain the pool.
Why did my pool turn brown after I shocked it?
This is often iron from well water. Chlorine makes the iron come out of the water and show as brown or rust color. A metal treatment and filtering usually fixes it.
How do I remove metal stains from pool plaster?
Use a stain treatment made for the metal you have, then a sequestrant to keep it in the water. Stubborn stains may need an acid wash.
Does well water hurt a salt cell?
Hard well water causes scale to build up on the cell faster, so it needs more frequent cleaning.
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