High pH water: what alkaline tap does to soap, skin and fixtures

Here's a call I get a lot. Somebody has a softener, the hardness number came down like it should, and they still say the water feels slick and the soap still doesn't rinse. They think the equipment failed. Usually it didn't. There's a second number on their water that nobody mentioned, and around here it is often sitting well above where it ought to be. Austin and I end up explaining pH on a lot of kitchen floors.

How this was built: Figures come from Jones Air & Water's own 57-town water dataset, built from utility consumer confidence reports, DNR and EPA data, and our own in-home testing, pulled in 2026. Eleven of the 57 town records carry a measured pH. Every one of those eleven is in the table below, including the one that is under the line, because leaving it out would make the pattern look tidier than it is.

What the 8.5 line actually is

Before the numbers, the honest framing. The 8.5 figure is a secondary standard. Our own records call it exactly that in different words across different towns: a secondary standard, an aesthetic guideline, an EPA cosmetic limit. It is not a health limit and I am not going to pretend it is one.

That matters because high pH is the kind of thing a dishonest outfit could scare you about. What it actually costs you is comfort, soap, and the look of your fixtures. Those are real and worth fixing. They are not a danger to your family, and anybody telling you otherwise is selling something.

Every measured pH in our dataset

Ten of the eleven towns with a number are above 8.5. Our St. Clair record also flags high alkalinity and alkaline pH driving aggressive scaling, but gives no figure, so I have left it out of the table rather than invent one.

Two things jump out. The high pH cluster is overwhelmingly St. Charles County, and the figure 9.13 repeats across four separate towns. As with the sulfate numbers in these same records, that kind of repetition usually means shared or purchased source water rather than four coincidences. I would not state that as fact, but it is the obvious read.

Why your softener did not fix it

This is the practical heart of it. Hardness and pH are two different measurements of two different things, and a softener is built for one of them. Look at the table again: St. Charles has the highest pH in the set at 9.36 and some of the softest water at 8.9 grains. Cedar Hill has the hardest water in the set at 18 grains and the lowest pH at 8.12, which is under the line.

They run in opposite directions. So if you soften a high pH supply you will fix the scale and the spotting that come from hardness, and the slick feel driven by the pH will still be there. That is not a failed install. That is two problems and one machine.

Cedar Hill is the useful counter-example in the other direction. Its pH is legal at 8.12, but our record pairs it with measured alkalinity of 353 mg/L and calls that combination aggressive scale. pH and alkalinity are not the same number either, and a compliant pH does not promise you a gentle water.

What it does to soap, in our records' own words

Our town records describe the symptoms consistently, and they are the ones people actually complain about. Our Augusta record says the water eats through soap. Our Union record pairs the 8.72 pH with scale and soap scum and says soap will not lather. Our Lake St. Louis record says the water tastes flat and soapy and drives even more scum. Our Foristell record says it never quite rinses off.

The rinse complaint is the one worth naming, because people misdiagnose it constantly. Our Foristell record ties the slick soapy film on your skin directly to the 9.1 pH, and our New Melle record describes a slick feel at pH 9 and above. If you have been scrubbing harder because you assume there is soap left on you, our own notes say the film is coming from the water, not from your technique.

What it does to skin and hair

Here too the records are specific. Augusta: a filmy, dry, squeaky feel that dulls color. Foristell: the slick film on skin and the dull straw feel in hair. Wright City: skin tight and hair flat. New Melle: a slick film on skin and a chalky haze on glass.

I will add the obvious practical note. If you color your hair, our Augusta record is the one that mentions dulling color specifically, and that is the complaint I hear most from customers who moved here from somewhere with gentler water.

What it does to fixtures and glass

Chalky haze on shower glass, spotty dishes, dingy laundry, and scale on faucets run through nearly every one of these records. Our St. Charles record lists chalky scale on faucets and shower glass, spotty dishes and dingy laundry together, at 8.9 grains, which is not especially hard water. That combination of modest hardness and visible film is the signature of a high pH supply, and it is why people in these towns swear their water is harder than the number says.

What I would actually tell you to do

Straight answer: our dataset documents the pH problem thoroughly and does not prescribe a fix for it, and I am not going to invent one here. What I can tell you from the file is which part of your complaint is hardness and which part is pH, and those have different answers.

The hardness half is straightforward and it is most of the cost in these towns anyway. A softener sized to your actual grains handles the scale, the spotting and a good share of the laundry complaint. In the towns above, that is a 9 to 11 grain job in St. Charles County and a 17 to 18 grain job in Union and Cedar Hill, which are very different machines.

The pH half is a separate conversation and it depends on your number and your plumbing, which is exactly the sort of thing I would rather look at in person than guess at in a blog post. What I would not do is let somebody sell you a softener as a pH fix, or a pH fix you do not need because your real problem was 18 grains of hardness all along.

For where your town lands on hardness, see the hardest water towns we serve, ranked by the numbers, and for the county where most of this high pH cluster sits, St. Charles County town by town.

Frequently Asked Questions

Schedule a Free Water Test With Jones Air & Water

If your water feels slick and your soap never rinses, I can tell you in one visit how much of that is hardness and how much is pH. I test both at your sink, and if the honest answer is that a softener fixes most of it and the rest is not worth spending money on, that is what I will tell you.

Schedule your free water test or see the water softener systems we install for hardness in this range.