Protecting Wells from Contamination

How do wells get contaminated?

Contamination can come from the surface, through cracks or open casings, or from underground sources. Common causes include septic systems, livestock waste, fertilizers, chemicals stored near the well, flooding and poorly sealed or abandoned wells.

Some contaminants occur naturally in rock and soil, so a well can have problems even on clean land. That is another reason to test.

Wells vary in depth and construction. Shallow or older dug wells are generally more exposed to surface sources than deeper drilled wells, but any well can be affected if the casing or cap is damaged.

• Septic systems and animal waste
• Fertilizers and pesticides
• Fuel and chemical storage
• Flood water entering the wellhead
• Old, unsealed wells nearby

What should the wellhead look like?

The top of the well should be intact, with a secure cap, a sound casing that extends above the ground and ground that slopes away so water drains off. Cracks, loose caps and open vents give contaminants an easy path in.

Walk around the well regularly. Look for damage, standing water, animal activity and signs of digging or disturbance. A qualified well contractor can inspect and repair it.

Make sure rain and runoff flow away from the well and not toward it. Low spots around the wellhead collect water that can find its way down the casing. A contractor can advise on grading.

• Secure, intact cap
• Casing sticking up above ground
• Ground sloping away
• No cracks, gaps or open vents

How far away should livestock, manure and chemicals be?

Many jurisdictions set minimum distances between wells and potential sources of contamination, such as septic fields, manure storage and fuel tanks. These distances vary by state and county.

Ask your county health department or conservation district what applies to your property, and plan pens, feed areas, compost piles and chemical storage accordingly. When in doubt, keep more distance.

Septic fields and animal yards are the most common neighbors that cause trouble. If you are planning a new building, pen or compost area, map the well first and plan around it. Distance alone does not guarantee safety, because slope and soil decide which way water moves. A contaminant uphill of the well is more of a concern than one downhill at the same distance.

• Septic field
• Manure storage and animal yards
• Fuel tanks and chemical storage
• Compost piles

What should I do around the well?

Keep the area clear of stored fuel, pesticides, fertilizers and manure. Do not mix or rinse chemical equipment near the wellhead. Keep animals fenced away, and mow carefully, because equipment can strike and damage the casing.

Keep records of when the well was drilled, its depth, repairs and test results. These help a contractor diagnose problems later.

Think about chemicals you may not consider hazardous, such as fuel for equipment, old paint, oils and cleaners. Store them in sealed containers on a firm floor, away from the well and out of reach of children and animals.

• Fuel and oil
• Pesticides and fertilizer
• Manure and compost
• Chemicals used on equipment

What about old or unused wells?

Abandoned wells are a safety and contamination hazard, because they can provide a direct path for pollution and are a danger to children and animals. Many places require them to be properly sealed by a licensed contractor.

If you find an old well on your land, do not open or disturb it. Mark it, keep people and animals away and call your health department or a licensed well driller for advice on proper decommissioning.

Never use an old well as a place to dump trash or waste. It can send contaminants straight into groundwater, which may also supply your neighbors.

What should I do after a flood or if the water changes?

After flooding, avoid drinking well water until it has been tested and, if needed, disinfected. Ask your health department for specific instructions for your area, since the steps depend on the damage.

Changes in taste, smell, color or clarity can signal a problem. Stop using the water for drinking until you have tested it, and have a licensed contractor look at the system if needed. Use bottled water in the meantime.

Keep a stock of bottled water for emergencies, and know the phone number of a licensed well contractor before you need one.

• Keep bottled water on hand
• Know a licensed contractor
• Stop drinking if the water changes until tested

Last reviewed: November 12, 2026. Written by the Homestead & Small Farm Editorial Team. See our editorial policy.