If your home in Arnold gets its water from a private well, the paperwork from the day the well was drilled may be the most useful document you own. A well log, sometimes called a well completion report, records what the driller found underground and how the well was built. Before you order a lab test or buy a treatment unit, it helps to know what that record says.

Where to find the record

Start with the closing packet if you bought the house. Sellers often hand over the original completion report, pump installation paperwork, and service receipts. If you do not have them, ask the seller or previous owner whether they kept records. You can also contact the state agency that oversees water well construction in Missouri, which keeps completion reports filed by licensed drillers. Search by property address and by the owner name on the original permit. Older wells may have little or no paperwork on file, so a missing report does not mean the well cannot be used.

Depth and water zones

The log lists total depth and the depths where water was found. These details matter because a shallow well is exposed to different conditions than a deeper well drawing from rock below the surface. Arnold sits in an area where homes draw on a mix of water sources, so the depth on the record helps you think about the kind of water you are likely pumping. Depth alone does not tell you whether water is safe, but it guides which tests make sense first. Shallow wells are more likely to be affected by surface conditions, which is why many homeowners with shallow wells start with bacteria testing.

Casing and sealing

Look for the casing material and length, and whether the record notes grout or a seal around the top of the casing. The casing and seal help keep soil and surface water from running down the outside of the well. Gaps in the seal, a cracked well cap, or a wellhead set below ground level are worth noting, especially if you plan a visual inspection. A licensed well contractor can tell you whether a seal looks sound and can spot damage that a paper record cannot show.

Static level, pumping level and yield

Many logs list the static water level, which is how far down the water sits when the pump is off, along with the pumping level or yield measured during the original test. Compare those notes with what you see at home. A pump that cycles often, a tank that loses pressure quickly, or a well that runs low during heavy use can point to a problem with the pump, the pressure tank, or the water supply itself. The log gives you a baseline, so when something changes, you have a reference point.

Geology notes

The driller's notes describe the layers they passed through, such as soil, clay, gravel, sandstone, or limestone. Those descriptions can help explain why water tastes or smells the way it does, and they can hint at minerals you may encounter. Hard water is common in the region, and a driller's notes may show where mineral-bearing rock was struck. Keep in mind that these notes are a field description, not a laboratory result. They suggest what to test for, but they do not replace a water test.

Turning the record into a testing plan

Once you have the log, make a short list before calling a lab. Note the well depth, casing details, and any water zones. Then match those facts to what you have observed in the house. Rotten egg odor, staining, cloudy water, or a change in taste each point toward different tests. Well owners in the south and west part of Arnold, near the mining area in southwest Jefferson County, should consider including lead on their sampling list. Ask the lab which containers and sampling steps it requires, because a poorly collected sample can give a misleading result.

Questions to bring to the driller or lab

  • Does the record match the well I have now, or was the well replaced or deepened since it was drilled?
  • Was the well sealed at the top, and does the seal still look intact?
  • Which tests fit my well depth, my water history, and any smells or stains I notice?
  • What sample containers and handling steps does the lab require?

When the paperwork is missing

If there is no record, start with a visual check of the wellhead and a water test before you buy any equipment. A licensed well contractor can estimate construction details from the visible parts and recommend the right tests. Missing paperwork can happen with older homes in and around Arnold, and it does not mean the water is unsafe. It only means you need to gather the information another way, one step at a time.