Well test kits range from a handful of strips to a laboratory panel covering dozens of parameters, and the useful one sits in between: a baseline that covers what every well should be checked for, plus the specific things known to occur in your area. Buying the largest available panel mostly pays for reports of absence.
The baseline every well should cover
Coliform bacteria, because it is the indicator of surface influence reaching the well and it has no taste or appearance. Nitrate, which matters particularly for infants and is common near agriculture. pH, which decides whether the water is corroding your plumbing and affects how other treatment behaves. Hardness, iron and manganese, which drive most of the equipment decisions. And total dissolved solids as a general indicator. That panel answers most treatment questions and costs a fraction of a comprehensive scan.
Then add what is local
Arsenic occurs naturally in groundwater across large areas and has no taste, colour or smell. Radon matters in some geologies. Fluoride occurs naturally in some aquifers. Agricultural chemicals matter near cropland, and fuel related compounds near old tanks or filling stations. Local health departments, state geological surveys and neighbouring well owners all know what turns up locally, and a short conversation before ordering usually adds one or two parameters that a generic kit would have missed.
Sampling properly, because it changes the result
Use the bottles the laboratory supplies, since some contain preservative and some are sterile, and follow their instructions exactly rather than approximately. Bacteria samples need a sterile technique and a short holding time, which is why the courier arrangement matters as much as the kit. Metals from plumbing, lead especially, need a first draw sample from a tap that has stood for hours, while a sample representing the well itself is drawn after running the tap. Sampling the wrong way produces a confident and useless number.
When to test
Annually for bacteria and nitrate, since both change and neither is visible. Every few years for the wider chemistry. And immediately after flooding or heavy run off near the wellhead, work on the well or pump, any change in taste, smell or colour, a new baby or pregnancy in the household, or a neighbour's well testing positive. The EPA notes private wells are not federally regulated under the Safe Drinking Water Act, so this schedule is entirely the owner's to keep. Our well test guide covers laboratory packages.
Questions people ask about well test kit
What should a basic well test cover?
Coliform bacteria, nitrate, pH, hardness, iron, manganese and total dissolved solids, plus anything known to occur locally.
Are strip kits enough for a well?
No. They are useful triage for hardness and chlorine, but bacteria, nitrate and metals need an accredited laboratory.
How often should I test?
Bacteria and nitrate annually, wider chemistry every few years, and immediately after flooding, well work or any change in taste or colour.
Does how I take the sample matter?
Considerably. Bacteria need sterile technique and short holding times, and lead needs a first draw sample from a tap that has stood.