How Do I Protect My Well From Surface Runoff?

Are you worried that surface runoff could carry contaminants into your well and affect the water you drink?

How Do I Protect My Well From Surface Runoff?

This article guides you through practical actions you can take to protect your well from surface runoff and explains how safe it is to drink untreated well water. You’ll find steps for assessing risk, physical protections, monitoring, treatment options, emergency response, and long-term maintenance so you can make informed decisions for your household.

Why surface runoff threatens wells

Surface runoff is water from rain, melting snow, or irrigation that moves across the ground surface. When it travels over land, it can pick up contaminants and carry them into areas where they can reach your well.

You need to understand the pathways and common contaminants so you can prioritize protections that make the biggest difference on your property.

Common contaminants carried by runoff

Runoff can transport a wide range of contaminants depending on land use and local conditions. Typical contaminants include pathogens (bacteria, viruses, protozoa), nutrients (nitrate, phosphate), pesticides and herbicides, petroleum hydrocarbons (oil, gasoline), heavy metals, sediment, road salts, and organic chemicals.

Knowing which contaminants are likely near your well helps you choose appropriate testing and treatment.

How runoff reaches your well

Runoff can reach your well by flowing across the ground into areas where water infiltrates, by moving down the outside of a poorly sealed well casing, along utility trenches or animal paths, and by raising the local groundwater level so contaminants infiltrate shallow aquifers.

Both surface flow and shallow subsurface flow can introduce contamination; deeper aquifers are more protected but can still be affected if well construction is inadequate.

How safe is it to drink untreated well water?

Untreated well water is not automatically safe. Many private wells test safe, but some contain contaminants that pose acute or chronic health risks. The safety of your well water depends on well construction, local land use, groundwater geology, and how well you maintain the well and manage nearby risks.

You should assume untreated water could be unsafe unless you have recent test results showing it meets relevant health-based standards.

Acute vs chronic health risks

Pathogens (like E. coli, Giardia, Cryptosporidium, norovirus) cause acute gastrointestinal illnesses that appear quickly after exposure. Chemical contaminants such as nitrates, pesticides, and heavy metals can cause chronic health issues that develop over months or years—examples include methemoglobinemia in infants (from high nitrate), some cancers (linked to long-term exposure to certain organic chemicals), and kidney or neurological damage (from heavy metals).

Understanding the difference helps you prioritize testing and treatment: test for bacteria frequently and test for chemicals when land use or symptoms suggest exposure.

Signs your well water might be unsafe

You might see warning signs such as cloudy or discolored water, unusual odors or tastes, staining of fixtures, dead or sick animals that drink from the source, or household illnesses after heavy rains. However, many contaminants are colorless and odorless, so testing is the only reliable way to confirm safety.

If you notice changes in water quality or health issues in your household, act quickly and test the water.

Regulations and responsibilities

Private wells supplying individual households are generally not regulated by national drinking water rules the way public systems are. That means you are responsible for testing, maintenance, and treatment.

Local or state health departments often provide testing services and guidance. Always check local regulations related to well construction, setbacks, and abandonment to ensure compliance.

When to contact authorities or professionals

Contact your local health department, environmental agency, or a licensed well contractor when you suspect contamination, after flooding, when you need well repairs, or when planning significant changes to your property that affect drainage. Professionals can advise on testing, safe disinfection, and necessary repairs.

Site assessment: How to evaluate your property

A simple property assessment identifies the highest risks to your well. Walk your property and map potential contaminant sources, topography, and how water moves across the land toward the well.

Assess during and after a rain event if possible so you can see actual flow paths and pooling areas.

Steps for a basic site assessment

• Locate the well and any finished-floor reference point, septic system, livestock areas, chemical storage, driveways, and low spots.
• Identify surface flow paths and where runoff concentrates.
• Note slope direction and steep areas that accelerate runoff.
• Check for erosion, gullies, or paths that direct water toward the well.
• Determine soil type and whether it drains quickly or holds water.

These observations help you prioritize grading, barriers, and source controls that reduce runoff reaching the well.

How to measure well setback distances

Setbacks are minimum recommended distances between your well and potential contamination sources. Local codes vary, but the following table shows common recommended setbacks used in many jurisdictions.

If your well is closer than recommended to any of these sources, consider relocation, additional protective measures, or enhanced testing and treatment.

Physical protection measures

You can reduce runoff-related contamination with a layered approach: protect the well itself, control surface water, and manage contaminant sources. Combining these strategies provides the best defense.

Think of protections in terms of prevention (keep contaminants away), diversion (keep runoff away), and fortification (make the well itself resistant).

Well casing, cap, and sanitary seal maintenance

A securely fitted well cap and an intact casing with a proper sanitary seal are your first line of defense. The cap should be vermin-proof and vented with a screened vent; the casing should extend above ground (commonly 12-18 inches or more depending on local code) to prevent floodwater entry.

Inspect annually and repair any cracks, gaps, or missing seals promptly. If your well cap is loose or rusted, replace it.

Surface concrete apron and grading

A concrete apron or collar around the wellhead prevents water from pooling directly next to the casing and directs runoff away. The apron should slope away from the well and be sealed around the casing.

Proper grading is essential: create a slope of at least 2% (about 2 feet drop over 100 feet) away from the well so that surface water flows away rather than toward the wellhead.

Protective pits, vaults, and coverings

In flood-prone areas, consider raising the wellhead, using watertight well caps, or installing a well pit or vault designed to prevent floodwater entry. Avoid enclosing the well in a structure that traps moisture and causes corrosion; any enclosure should be ventilated and designed by a professional.

Landscaping and buffers

Use vegetation and buffers to slow runoff and filter contaminants. Deep-rooted grasses, native plants, and riparian buffers reduce erosion and uptake nutrients. Avoid planting mulch or organic berms directly against the well casing, which can hide damage and retain moisture.

Managing surface runoff sources

You reduce risk most effectively by controlling what can enter runoff in the first place. Manage chemicals, fertilizers, livestock, fuel, and septic systems so contaminants are not available to be carried toward your well.

Source control is usually lower cost and more reliable than treating contaminated water later.

Managing fertilizers, pesticides, and household chemicals

Store pesticides, herbicides, fertilizers, and hazardous household products in secure, covered areas upslope and far from the well. Follow label instructions and apply chemicals at recommended rates to minimize excess that can run off. Consider integrated pest management to reduce chemical use.

Use garage or shed storage instead of outdoor shelves. Keep spill kits handy and clean up any spills immediately with appropriate absorbents.

Livestock and manure management

If you have livestock, maintain fenced setbacks to keep animals away from the well and prevent direct contamination. Use off-stream watering systems, collect and compost manure away from the well, and manage grazing to limit bare ground that produces runoff.

Rotational grazing and manure storage with proper liners can greatly reduce pollutant loads.

Septic system maintenance

Septic systems are a common source of nitrates and pathogens. Have your septic inspected and pumped regularly—typically every 3-5 years depending on use. Ensure the drainfield is functioning, and do not direct roof drains, driveway runoff, or sump pumps to the leach field.

If your septic is uphill of the well or too close, consider relocating or upgrading the system.

Road, driveway, and petroleum control

Seal and maintain driveways and areas where vehicle fluids can accumulate. Use vegetation strips to intercept road runoff. Store fuel and vehicle fluids in secondary containment and away from the well.

Stormwater controls and erosion prevention

Techniques that slow, store, and infiltrate runoff reduce the volume and contaminant load that might reach your well. These methods often provide landscaping or productivity benefits.

Combining small measures across the landscape—green infrastructure—can substantially lower runoff risk.

Rain gardens, swales, and infiltration basins

Rain gardens and vegetated swales are shallow depressions planted with native vegetation that capture runoff, allow it to infiltrate, and filter pollutants. Place them downslope from impervious areas but not directly adjacent to the well.

Infiltration basins hold stormwater temporarily and let it percolate slowly; they should be sited so they don’t send contaminated water toward the well.

Permeable surfaces and driveway design

Replace impermeable surfaces where feasible with permeable pavers or gravel to reduce surface flow. For driveways, use crowned profiles or drains to divert water away from the well.

Erosion control and riprap

Use riprap or erosion control blankets on steep channels to prevent gullies that channel water toward the well. Stabilize bare soil with mulch and vegetation as soon as possible after disturbance.

Water testing and monitoring

Regular testing is your only reliable indicator of water safety. Establish a testing schedule and test more often if conditions change (heavy rains, nearby construction, new contaminants on the property, changes in taste or smell).

Document results so you can spot trends over time.

Which tests to run and when

The following table summarizes typical tests for private wells, recommended frequencies, and triggers for additional testing.

Work with a certified lab and follow their instructions for sample collection to avoid false positives or negatives.

Interpreting test results

Compare results to drinking water standards (e.g., EPA Maximum Contaminant Levels) and local public health guidance. Even if levels are below regulatory limits, some users—pregnant people, infants, immunocompromised individuals—may need stricter criteria.

If bacteria are present, assume a health risk and do not drink water until it is disinfected and retested.

Treatment options for contaminated well water

If testing shows contamination, treatment can protect your household. Choose treatment based on the contaminant type and whether you want point-of-use (single tap) or point-of-entry (whole-house) treatment.

Professional consultation is recommended for design, sizing, and ongoing maintenance.

Disinfection: shock chlorination and continuous chlorination

• Shock chlorination: Use chlorine bleach to disinfect the well and distribution system when bacteria are detected. This is a short-term remedy and may need to be repeated if the source of contamination isn’t addressed.
• Continuous chlorination: Dosing of chlorine at the wellhead protects against recurring bacterial contamination. It requires monitoring of chlorine residual and corrosion control.

Chlorine is effective against most bacteria and viruses but less effective against some protozoa (Cryptosporidium) and doesn’t remove chemicals.

UV disinfection

Ultraviolet (UV) systems inactivate bacteria, viruses, and protozoa (including Cryptosporidium if properly sized and water quality is low in turbidity). UV does not remove chemicals, nitrates, or particulates and requires pre-filtration for turbid or iron-rich water.

Filtration and specialized treatment

• Sediment filters: Remove sand, silt, and particles that can protect pathogens from disinfection.
• Activated carbon filters: Remove many organic chemicals, pesticides, and taste/odor compounds.
• Reverse osmosis (RO): Effective for nitrates, many dissolved solids, some metals, and certain organics when installed at point-of-use.
• Ion exchange: Used to remove hardness, nitrate, or certain metals.
• Aeration/oxidation and filtration: Effective for dissolved iron, manganese, and some volatile organics.
• Distillation: Produces high-purity water but is energy-intensive and usually point-of-use.

Select systems based on test results and household needs. Often, a combination of pre-filtration, disinfection, and targeted treatment provides the best protection.

Emergency actions after contamination event (flooding, heavy runoff)

If flooding or a heavy runoff event has occurred near your well, take immediate precautions: avoid using the well water for drinking, cooking, or brushing teeth until you have it tested and cleared.

Boiling water is effective against pathogens but does not remove chemicals.

Steps to take after flooding

1. Stop using the water for drinking and prepare safe bottled water or obtain alternate water.
2. Have the well professionally inspected for structural damage.
3. Shock-chlorinate the well and distribution system if advised by health authorities or a well professional.
4. Test for bacteria and other likely contaminants once disinfection protocols are followed.
5. Replace any filters that were submerged or potentially contaminated.
6. Do not use the well until testing confirms safety.

Document the incident, photographs, and communication with authorities for future reference.

Long-term maintenance and record keeping

Consistent maintenance and records reduce long-term risks. Keep a file with well construction details, test results, service records, repairs, and any permits or communications with local agencies.

A maintenance checklist helps you stay on schedule.

Suggested maintenance schedule

• Annual: Test for bacteria; visually inspect wellhead, cap, and casing.
• Every 1–3 years: Test for nitrates, pH, hardness, and any site-specific chemicals.
• Every 3–5 years: Comprehensive testing for metals and less-common contaminants as recommended.
• Every 3–5 years: Have a licensed well contractor inspect well condition, pump performance, and electrical controls.
• As needed: Shock chlorination after contamination events; immediate repairs for damaged casing or caps; pump replacement when performance declines.

Record the dates and results of all maintenance and testing.

Abandoning old wells

Seal unused wells professionally. Abandoned wells are direct conduits for surface water and contaminants to reach groundwater. A properly sealed well protects not only your water but also your neighbors’ groundwater.

Contact local authorities for regulations and licensed contractors for sealing.

Cost considerations and funding assistance

Costs vary widely by region and the level of protection. Simple fixes like regrading and installing a concrete apron can be relatively inexpensive, while installing a new well, raising a wellhead, or whole-house treatment systems can cost thousands to tens of thousands of dollars.

Look into state or local cost-share programs, grants, and low-interest loans aimed at rural homeowners or small communities; conservation districts and health departments often know of assistance programs.

Typical cost ranges (approximate)

Check local contractors and obtain multiple quotes before major work.

Frequently asked questions

You’ll find short answers to common questions about protecting wells from runoff and water safety.

What should I do first if I suspect my well is contaminated?

Stop drinking the water, use bottled water, test for bacteria immediately, and contact your local health department or a licensed well contractor for guidance on disinfection and further testing.

How often should I test my well for bacteria?

Test at least once a year and after heavy rains, flooding, septic work, or if anyone in your household becomes ill with gastrointestinal symptoms.

Can I simply boil contaminated well water?

Boiling kills pathogens but does not remove chemical contaminants like nitrates, pesticides, or heavy metals. Boiling is a useful temporary measure for biological contamination only.

Is it enough to disinfect the well once?

If bacterial contamination recurs, it indicates a source of contamination (surface runoff, septic failure, cracked casing) that must be fixed. Repeated disinfection without addressing the source is not a long-term solution.

How close can my livestock or septic system be to my well?

Local regulations set minimum setbacks, but typical recommendations are 50–200 feet for septic systems and manure storage, and at least 50 feet for livestock areas. Greater distances are safer.

Can a new well eliminate contamination risk?

A properly sited and constructed well in a good aquifer is much safer, but no well is immune to contamination if surface runoff reaches groundwater or the well is poorly constructed. Source control and proper siting reduce risk.

Selecting a well contractor or water treatment professional

Choose licensed, insured, and locally experienced professionals. Ask for references, proof of licensing, and detailed written estimates. For treatment systems, ask about ongoing maintenance costs, replacement filter availability, and warranty terms.

You can also consult local health departments for lists of licensed well contractors and certified labs.

Final thoughts and action steps

You have practical options to reduce the risk that surface runoff poses to your well: assess your property, secure and maintain the wellhead, improve grading and drainage, control contamination sources, test regularly, and install appropriate treatment if needed.

Start by testing your water and performing a simple site assessment. From there, prioritize fixes that keep contaminants away from the well. Long-term vigilance—regular maintenance, testing, and record keeping—will protect your water supply and your household’s health.

If you need help getting started, contact your local health department or a licensed well professional for tailored advice. Taking action now can prevent costly repairs and health risks later.