Many Missouri homes sit on farm ground, near gardens, or beside a neighbor's pasture or barn lot. Fertilizer, manure, and stored chemicals can move through soil and reach groundwater when they are kept or spread too close to a private well. This guide helps a homeowner walk the property and spot the common siting issues. It does not replace a water test, and it cannot tell you whether your water is safe to drink.
What to look for on the surface
- Manure piles, feed lots, or pens that slope toward the well or toward low ground near it.
- Bulk fertilizer bins, spreader wash areas, or mixing spots close to the well house.
- Pesticide or herbicide containers with stains, leaks, or open lids.
- Ditches or drainage swales that carry runoff from fields or driveways straight toward the wellhead.
- Compost heaps or animal disposal areas placed uphill from the well.
Why slope and soil matter
Rain and snowmelt carry dissolved material and fine particles downhill and into low spots. Soil depth, rock type, and the presence of cracks in bedrock all change how fast surface material can reach the aquifer. Across Missouri, some properties have thin soil over fractured rock, while others have deeper soil that slows downward movement. You cannot see the underground layers from the surface, but you can note which direction water runs after a heavy rain and where it collects.
Compounds you may hear about
Nitrate is a form of nitrogen that moves easily through soil and is one of the most common compounds tested in private wells. Fertilizer and manure are typical sources. Certain pesticides and bacteria from animal waste can also reach water. A standard test panel does not cover every compound, so choose tests based on what is stored, spread, or applied on the property and on the land uphill from the well.
Walk-through steps
- Pull your well completion record and mark the well location on a simple sketch of the property.
- Walk the ground in a circle around the well, noting every storage area, spreading zone, and animal space.
- Follow the slope of the land and any ditches to see where runoff would travel after rain.
- Photograph each concern and note its distance from the well by pacing or measuring with a tape.
- Check whether any containers are labeled, dated, and stored off the ground in a covered area.
Setting separation distances
Local rules and the construction record of your well determine which separation distances apply to new storage or spreading near a well. Missouri homeowners can ask their county health office, their county extension office, or the state environmental agency what is expected for their property. Ask before you build a new manure pad, fertilizer bin, or chemical shed, since moving a structure is much easier than correcting a problem later.
Testing after you find a concern
If you spot a storage or runoff issue, a water test is the next step. Use a certified laboratory, ask for a panel that includes nitrate and any compounds you use on the land, and keep the sample collection instructions handy. Repeat testing after heavy rain or after a change in land use, such as a new pasture or a change in fertilizer practice. A single result describes the water on the day it was collected, so trends over time are more informative than one number.
Keep a simple record
- Dates when manure is spread, hauled, or moved near the property.
- Fertilizer and pesticide purchases, storage locations, and any spills.
- Photos of runoff paths after storms and notes on where water pooled.
- Test results with the sample date and the panel used.