You get your well water tested, the results come back, and it is a wall of numbers with letters next to them. Iron 1.2. Hardness 220. pH 6.9. Sulfate 180.
What do any of those mean? Is 1.2 iron bad? Is 220 hardness dangerous?
There is a real answer, and it comes from two sources most people never look at: the EPA and the U.S. Geological Survey. Once you know what their numbers say, a water test stops being a mystery. Here is the plain version.
Two kinds of standards, and the difference matters
The EPA sets drinking water standards, but it sets two very different kinds, and mixing them up is where confusion starts.
Primary standards are about health. They are legally enforceable for public water systems and they cover things that can actually make you sick, like bacteria, nitrate, lead, and arsenic. When one of these is exceeded, it is a genuine safety issue.
Secondary standards are different. The EPA calls these Secondary Maximum Contaminant Levels, or SMCLs. They are not about health and they are not legally enforceable. They are guidelines for things that affect how your water looks, tastes, smells, or behaves. Staining, odor, scale, bad taste.
That distinction is the whole game. Most of what makes Central Florida well water annoying, the iron and the sulfur and the hardness, falls under secondary standards. That means it is a nuisance, not a poison. It will stain your sinks and wreck your coffee, but at typical levels it is not making you sick.
That is genuinely good news, and it also means these problems are about comfort and cost, not danger. You get to decide how much they bother you.
Now, the actual numbers.
Iron: the EPA guideline is 0.3
The EPA secondary standard for iron is 0.3 milligrams per liter, often written mg/L. Above that level, iron starts to cause the problems iron is famous for.
Orange or reddish brown stains on sinks, tubs, and toilets. Rusty looking water, especially the first draw in the morning. A metallic taste. Stains on laundry. Buildup inside pipes and water heaters.
Central Florida wells very commonly run above 0.3. It is one of the most frequent things we find. Iron is a nuisance issue, so it is not a health emergency, but at high levels it is a real quality of life problem and it slowly damages plumbing and fixtures.
Iron is usually a job for water treatment, often paired with aeration, which turns the dissolved iron into a particle a filter can catch.
Manganese: the small number with a twist
Manganese often shows up next to iron on a test, and it causes similar staining, except the stains are black or dark brown instead of orange.
The EPA secondary standard for manganese is 0.05 mg/L, much lower than iron because it takes far less manganese to stain.
Here is the twist worth knowing. Manganese is mostly a nuisance, but unlike iron, it also has a separate health advisory. The EPA has noted that too much manganese can be a concern, especially for infants under six months old, because their bodies are still developing. The staining shows up at 0.05, but the health advisory level is higher, at 0.3 mg/L over a short period.
For most households this is still a staining and taste issue. But if you have a baby in the house and your manganese is high, that is a reason to treat it, not just to live with the stains. This is exactly the kind of thing a test reveals and a sniff never would.
Sulfur: the rotten egg number
The rotten egg smell in well water is hydrogen sulfide gas. Here is something that surprises people: the EPA does not set a secondary standard number for hydrogen sulfide at all.
Why not? Because you can smell it at levels far too low to measure easily. Your nose is a better detector than most tests. If your water smells like rotten eggs, you have hydrogen sulfide, and no number is needed to confirm it.
What a test sometimes shows instead is sulfate, a related compound. The EPA secondary standard for sulfate is 250 mg/L. High sulfate can give water a bitter taste and, at high enough levels, a laxative effect, especially for people not used to it.
Sulfur smell is usually solved with aeration, which we covered in detail in our piece on rotten egg odor. It is a nuisance issue, but a strong one, because few things drive people out of a shower faster.
Hardness: not an EPA number at all
Here is where the EPA hands off to the U.S. Geological Survey.
Hardness is caused by calcium and magnesium dissolved in the water. The EPA does not regulate it, not even as a secondary standard, because those minerals are not harmful to drink. In fact they are minerals your body uses.
But hard water is a practical headache. Scale buildup on faucets and inside water heaters. Soap that will not lather. Spots on dishes and glasses. Dry skin and hair. Appliances that wear out sooner.
The USGS uses a simple scale, measured in mg/L as calcium carbonate:
- Soft: 0 to 60
- Moderately hard: 61 to 120
- Hard: 121 to 180
- Very hard: more than 180
Central Florida sits on limestone, which is loaded with calcium. So our water is often hard or very hard. A reading of 220 is squarely in very hard territory, and yes, that will scale your pipes and eat your soap, but no, it is not dangerous to drink.
One unit note, because softener companies use a different one. Hardness is sometimes given in grains per gallon, or gpg, instead of mg/L. One grain per gallon equals about 17 mg/L. So very hard water above 180 mg/L is roughly above 10 grains per gallon. If a salesperson quotes your hardness in grains, that is the conversion.
Hardness is the job a water softener is actually built for. Not iron, not sulfur, not bacteria. Hardness. If someone tries to sell you a softener to fix a smell, they are selling you the wrong machine.
pH: the one that quietly causes trouble
pH measures whether water is acidic or basic, on a scale where 7 is neutral. The EPA secondary range is 6.5 to 8.5.
Water below 6.5 is acidic, and acidic water is a slow problem. It corrodes pipes and fixtures over time and can pull metals like copper out of your plumbing. Sometimes those blue green stains on fixtures are the real tell.
Central Florida water is often on the harder, more basic side because of all the limestone, but acidic wells do exist here, and low pH is worth catching early because the damage it does is gradual and expensive.
So what should you actually do with your test?
Put the numbers next to the guidelines above and you can read your own report.
- Iron over 0.3, expect orange stains. Treatable.
- Manganese over 0.05, expect black stains. Treatable, and check the health note if you have an infant.
- Rotten egg smell, that is hydrogen sulfide. Treatable.
- Hardness over 120, your water is hard. Over 180, very hard. Treatable with a softener.
- pH under 6.5, acidic and slowly corrosive. Treatable.
Almost none of this is about safety. It is about comfort, cost, and protecting your plumbing. The one exception is the primary standard items, bacteria and nitrate, which are about health and which a basic field test will not catch. That is why a full lab test matters, especially before you buy a home or if anything about the water changes.
Get numbers you can trust
The catch with all of this is that the guidelines only help if the test is accurate and complete. A cheap strip that checks two things will not tell you about bacteria, nitrate, or manganese.
We run free in home tests for the common items and send samples to a certified lab when you need the full picture. Either way, you get real numbers and a plain explanation of what each one means for your water and your house. No fear, no upsell, just what is actually in there.
Learn what our testing covers on our water testing page, or get in touch and we will come test your well. We serve Hernando, Pasco, Citrus, and Hillsborough Counties, and every job carries a one year warranty on labor and materials.