Wisconsin private wells: 3 definition checks explained

Key takeaways

• Check public supply status before comparing counts.
• Keep connection and people counts separate.
• Check both individual and combined well capacity, excluding residential and fire protection wells.

Everything here is Wisconsin's. The rules do not carry over to other states, even close neighbors, so if you live somewhere else, look up that state's own agency and its definitions before you use any figure below.

What is a private well in Wisconsin?

In Wisconsin, the Department of Natural Resources (DNR) describes a private well as a well that is not part of a public water supply. Start there: is your well part of a public water supply? If it is not, your well matches the first part of the DNR's description. That question comes first in this post because the DNR's definition opens with it.

The DNR also says private wells are usually wells that serve a single home or farmhouse. The word to notice is "usually." That line describes the typical setup and helps you picture a private well, but it does not decide the question on its own. The two numeric limits in the DNR's description do more of the sorting work, and the next section covers them.

How many connections and people does a private well serve?

The DNR says private wells have fewer than 15 connections and serve fewer than 25 people. These two limits are the most concrete part of the description, so they are the place to start a careful comparison.

The two tests are separate. The DNR pairs them with "and," so you compare the well on connections and on people, one at a time. Passing one test does not answer the other.

Counting takes some care. Count every connection the well supplies, not only the one in the kitchen. Think through everyone the well serves, such as guests, workers, and tenants, not only the people who live in the main house. If your property has a rental unit, a shop, or a second dwelling, check whether water from this well reaches it.

Record which buildings the well supplies, and ask the DNR about any connection you cannot classify. Keep the two counts separate so the connection test and the people test do not blur together.

Who is responsible for a private well?

The DNR says that, unlike public water systems, protection and maintenance of a private well is largely the responsibility of homeowners. That sentence is about who carries the work, and it is the part of the definition most directly about your own role as an owner.

Plan separately for protection and maintenance tasks, how often they happen, and what they cost. Treat any detail about a specific task as a separate question.

Owning a private well means that much of the work of looking after it falls to you. If you are buying a home with a private well, or inheriting one, build that responsibility into your plans for time and money before the first problem shows up. Base your plans on your own situation, and organize a private well file.

The table below puts the DNR's definitions, exclusions and filling and sealing rule side by side.

When does a well become a high capacity well?

The DNR defines a high capacity well as a well that has the capacity to withdraw more than 100,000 gallons per day, or a well that, together with all other wells on the same property, has a capacity of more than 100,000 gallons per day.

That definition has two routes. The first looks at a single well: does that well have the capacity to withdraw more than 100,000 gallons per day? The second looks at the property as a whole: do all the wells on the same property, together, have a capacity of more than 100,000 gallons per day? The second route brings the property's other wells, apart from residential and fire protection wells, into the comparison.

The DNR uses two phrases for this idea. The definition speaks of a well that "has the capacity to withdraw" water, and the exclusion speaks of "pumping capacities." Both phrases describe capacity, the same measure the 100,000 gallon figure limits.

Because the threshold is about capacity rather than about connections or people, it needs its own comparison. Do not fold it into the counts from the earlier section.

Do residential wells count toward a property's high capacity total?

Under the DNR's description, no. Residential wells and fire protection wells are excluded from the high capacity definition, and their pumping capacities are not included in the calculation of a property's well capacity.

The exclusion names only these two kinds of well. It does not remove any other well on the property from the calculation, and the definition's phrase "all other wells on the same property" still applies to them. For a property with more than one well, the first job is to sort each well into one of three groups: residential, fire protection, or other.

Is a fire protection well a kind of residential well?

The DNR lists residential wells and fire protection wells separately. Keep both groups separate when you sort a property's wells.

When a well's use is unclear, leave it unsorted until you can answer that question, rather than placing it in a group because it seems to fit.

Which way do the limits point?

The private well limits are "fewer than" limits, and the high capacity threshold is a "more than" limit. Two sets of wording point in opposite directions, and that is where a comparison is easiest to get wrong.

A count equal to a private well limit does not meet it. Exactly 15 connections is not fewer than 15, and exactly 25 people is not fewer than 25. A capacity equal to the high capacity figure does not go over it, so exactly 100,000 gallons per day is not more than 100,000 gallons per day.

Because the rules are written as exact cutoffs, estimates need care. A rough count of connections can land on either side of 15, so count exactly rather than guessing or rounding toward the answer you expect.

Units also matter. The high capacity threshold is in gallons per day, so a capacity figure given in another unit has to be converted to gallons per day before it is compared with 100,000. The private well limits count connections and people, so they need no conversion.

Who can fill and seal a well?

The DNR's well filling and sealing page states that, as of June 1, 2008, only licensed well drillers and pump installers can fill and seal wells under Wisconsin law.

Before any filling or sealing work, talk with a licensed well driller or pump installer. Use the well driller credential checks to prepare your questions.

Check a farm in 5 steps

Here is a step-by-step check using only the DNR figures covered above. A farm is a useful test case because it can have more than one well in one place, which is where the second capacity route matters.

Consider a farm where the main well supplies the farmhouse, and a separate well is a fire protection well for the barn. Suppose the farmhouse well is residential. Work through the farm in this order:

1. Public supply. Ask whether the farm's well is part of a public water supply. If it is not, it matches the first part of the DNR's description. If it is, the private well description does not fit it.
2. Connections. Count every connection the well supplies. The limit is fewer than 15, so a count of 15 does not meet it. A count below 15 meets this limit.
3. People. Count everyone the well serves. The limit is fewer than 25, so a count of 25 does not meet it. A count below 25 meets this limit.
4. Sorting wells. List every well on the farm. The fire protection well goes into the excluded group, so its capacity is left out. The farmhouse well is residential, so its capacity is also left out.
5. Capacity. If the farm has other wells that are neither residential nor fire protection, compare each remaining well's capacity on its own with more than 100,000 gallons per day, then compare their combined capacity with that figure. If the combined capacity is more than that, the second route applies to the property. If it is not, the property does not meet the second route on these figures. If the farm has no such wells, there is nothing left to compare on the second route.

Each step gives a yes or no answer, and only the last step uses the 100,000 gallon figure.

Illustrative example: compare the counts

Both counts meet the private well limits. This comparison does not settle any capacity question.

What can you check today?

Today, write down whether your well is part of a public water supply and record its connection and people counts. Keep uncertain entries marked as questions for the DNR rather than guessing. Save your notes with your well records so you can return to the same comparison later.

What if a count or capacity is unclear?

Leave the comparison unresolved until you can establish the count or capacity. A count you cannot pin down cannot be placed cleanly on either side of a limit, and a capacity you cannot express in gallons per day cannot be compared with the threshold yet.

In that case, report the uncertain part instead of filling it in with a guess. Take an open question about these rules to the DNR.

Checklist for your property

Use these actions to check your own well against the DNR figures:

• Confirm whether your well is part of a public water supply.
• Count every connection the well supplies, and compare the count with fewer than 15.
• Count the people the well serves, and compare the count with fewer than 25.
• List every well on the property, and mark each one as residential, fire protection, or other.
• Convert capacities to gallons per day; compare each remaining well individually with more than 100,000 gallons per day, then compare their combined capacity with that figure.
• Write down your counts, the date you made them, and the source you used, so you have a record to show a professional or agency.