If you are outside the mains anywhere around Blanchard, Tuttle, Harrah, Luther, Choctaw or the country edges of Norman and Edmond, your water is almost certainly coming out of the central Oklahoma aquifer. Most people here call it the Garber-Wellington, after the two rock formations that hold the water.
It is a good aquifer. It is also one of the most studied in the state, and the reason it has been studied is worth knowing before you spend money on treatment.
What the US Geological Survey has found in it
Arsenic, naturally occurring, from the rock itself rather than from anything anybody did. USGS has measured concentrations in the confined part of the aquifer at up to 232 micrograms per liter. The federal drinking water limit is 10.
Alongside it: uranium, selenium, chromium, nitrate, chloride, fluoride and dissolved solids, all documented in the state's own groundwater reporting and in the USGS surveys of the aquifer.
None of this is a scandal and none of it is new. It is geology.
Why this matters more for you than for your neighbors in town
Here is the sentence from USGS that should decide what you do next. Public water supply wells in this aquifer are monitored by the state and treated to meet the standard. Shallow domestic wells are not monitored at all, and USGS has written plainly that owners “may be unknowingly ingesting” what is in them.
Norman is the clearest example. About a fifth of the city's water comes from its own wells in this aquifer, and when the arsenic limit was tightened, around half of those wells would not have met it. The city treats and blends to comply, and its water meets the standard today. A private well two miles outside the city limits, on exactly the same ground, has nobody doing any of that for it.
Now the part that costs people money
A water softener does not remove arsenic. It does not remove uranium or nitrate either.
Softening is ion exchange. It swaps calcium and magnesium for sodium, which is how it stops scale, spotting and the film in your shower. It is very good at that job and it is the wrong tool for this one. Carbon filtration, which handles chlorine, chloramine, taste and smell, is also the wrong tool for this one.
We will say that even though it is the cheaper sale, because the alternative is a customer who believes they are protected and is not.
What actually works
Reverse osmosis at the kitchen sink. It pushes water through a membrane fine enough to hold back dissolved solids, arsenic, uranium and nitrate, and it handles the water you drink and cook with — which is the water that matters for these particular contaminants.
That is why, on a well, we treat reverse osmosis as part of the answer rather than something to bring up at the end of a sales call.
The order of operations
- Test first. Not a sales demonstration with a drop bottle — a proper test, including the things a softener cannot fix. If you have never had the well tested, that is the whole job for now.
- Treat iron and sulfur before softening. Iron fouls softening resin. If there is iron in the water and it goes into the softener untreated, the softener's life gets shorter and nobody tells you why.
- Soften for the scale. That is the part you can feel, in the shower, on the glassware and in how long the water heater lasts.
- Reverse osmosis for what the rest cannot touch. Arsenic, uranium, nitrate, dissolved solids.
One more thing, since we are plumbers
On a well, the pump, the pressure tank and the treatment all have to be sized together. Treatment adds pressure loss. A system specified without looking at what is already in the well house is how a house ends up with soft water and no pressure, and the person who sold it is usually not the person who can fix that.
Our price is the same on a well as on city water, which is unusual — well builds normally get quoted higher. We would rather see the test first and tell you what it needs.
Sources. USGS Fact Sheet 2005-3111, Naturally Occurring Arsenic in Ground Water, Norman, Oklahoma, 2004. USGS Scientific Investigations Report 2006-5084 on groundwater quality in the central Oklahoma aquifer. Oklahoma Water Resources Board, Garber-Wellington Groundwater Basin staff report, 2019. All three are linked from our Your Water page.