Well Water Systems in Washington State: Complete Homeowner Guide

Last Updated: March 2026

Hundreds of thousands of Washington homes rely on private wells—particularly in rural areas, islands, and communities without municipal water. Understanding well systems, maintenance requirements, water quality, and Washington regulations helps protect your investment and your family's health.

Well Water Basics

How Wells Work

Drilling/Digging: Well extends into water-bearing formation (aquifer)
Casing: Steel or PVC pipe prevents collapse and contamination
Screen: Allows water in while keeping sediment out
Pump: Lifts water from well to pressure tank
Pressure Tank: Maintains system pressure, reduces pump cycling
Pressure Switch: Controls pump operation based on pressure

Well Types in Washington

Drilled Wells

Most common for residential use
50-500+ feet typical depth in Washington
4-8 inch diameter common
Steel or PVC casing
Most reliable long-term option

Dug Wells

Older, shallow (10-30 feet typically)
Large diameter (3-6 feet)
Higher contamination risk
Many being replaced with drilled wells
Not permitted for new construction in most areas

Driven Wells

Small diameter (2-4 inches)
Shallow depth (under 50 feet)
Limited to areas with sandy soil
Less expensive but less reliable

Washington Well Regulations

Department of Ecology Oversight

Water Right: May be required for large users
Permit-Exempt Wells: Most residential wells (up to 5,000 gallons/day)
Well Construction Standards: WAC 173-160

Well Drilling Requirements

Licensed well driller required
Well construction permit from Ecology
Well log filed with state upon completion
Decommissioning required for abandoned wells

No Permit Required For

Residential use under 5,000 gallons/day
Most household purposes
Half-acre or less irrigation

Permit Likely Required For

Large irrigation systems
Commercial or industrial use
Water exceeding permit-exempt limits
Water for multiple properties

Well Costs in Washington

New Well Installation

Component	Typical Cost Range
Drilling	$35-85 per foot
Pump Installation	$1,000-2,500
Pressure Tank (40-80 gal)	$300-800
Pressure Switch/Controls	$100-300
Pitless Adapter	$200-400
Well Seal	$100-200
Total (100' well)	$5,000-10,000
Total (300' well)	$12,000-25,000

Factors Affecting Cost

Depth to water: Deeper = more expensive
Geology: Rock drilling costs more than soft formation
Access: Remote sites add mobilization costs
Water quality: May need treatment systems
Pump type: Submersible vs jet pump

Ongoing Costs

Service	Typical Cost	Frequency
Water Testing (basic)	$75-150	Annually
Water Testing (comprehensive)	$200-500	Every 3-5 years
Pump Inspection	$100-200	Every 2-3 years
Pump Replacement	$1,500-3,500	Every 10-20 years
Pressure Tank Replacement	$300-800	Every 10-15 years
Water Softener Maintenance	$200-400/year	Ongoing

Water Quality in Washington

Common Water Quality Issues

Hard Water

Prevalent in much of Eastern Washington
Causes scale buildup in pipes, appliances
Leaves spots on dishes, fixtures
Treatment: Water softener

Iron

Common throughout state
Causes red/orange staining
Metallic taste
Treatment: Iron filter or oxidizing system

Manganese

Often accompanies iron
Black staining
Treatment: Similar to iron

Arsenic

Natural in some areas (Central/Eastern WA)
No taste or odor
Health risk—testing essential
Treatment: Reverse osmosis, specialized filters

Nitrates

From septic systems, agricultural runoff
Risk to infants (blue baby syndrome)
Treatment: Reverse osmosis, ion exchange

Bacteria (Coliform)

Indicates possible contamination
May signal well integrity issues
Treatment: Shock chlorination, UV, or chlorination

Required Testing

Washington recommends testing private wells annually for:

Coliform bacteria
Nitrates (especially if near septic or agriculture)

Additional tests based on local conditions:

Arsenic (in affected areas)
Lead (if older plumbing)
Radon (some areas of concern)

Where to Test

State Environmental Lab: DOH-approved labs list
County Health Departments: Many offer testing or referrals
Private Labs: DOH-certified labs throughout state

Finding Well Contractors

Required Licenses

Well Driller License: Issued by WA Department of Ecology
Pump Installer: May be separate license
General Contractor Registration: With L&I

Verify Credentials

Ecology Licensed Drillers Search
L&I Contractor Verification
Request insurance certificates
Check references

Questions to Ask

Are you licensed to drill in Washington?
How deep are wells typically in this area?
What's your estimate of the water table depth here?
Do you include pump installation?
What warranty do you offer?
How long will drilling take?
What happens if you don't find water?

Well Maintenance

Homeowner Responsibilities

Annual:

Test water quality (coliform, nitrates minimum)
Check pressure tank operation
Inspect wellhead for damage, proper seal
Monitor water pressure and flow

Every 3-5 Years:

Comprehensive water quality testing
Professional system inspection
Pressure tank inspection

As Needed:

Address any water quality changes immediately
Repair damaged wellhead or casing
Replace failing components

Signs of Problems

Reduced flow: Pump issue, well silting, or dropping water table
Air sputtering: Pump drawing air, water level dropping
Discolored water: Iron, sediment, or contamination
Bad taste or odor: Bacteria, sulfur, or chemical contamination
Higher electric bills: Pump running excessively
Pressure fluctuations: Pressure tank or switch issues
Sandy or silty water: Screen or casing failure

Well Pump Types

Submersible Pumps

Located inside well, below water
Most common for deep wells (25-300+ feet)
Quieter operation
More efficient, longer lasting
Harder to service (must pull from well)

Jet Pumps

Located at surface
Shallow well jet: 25 feet or less
Deep well jet: Up to 110 feet
Easier to access for service
Less efficient than submersible
More noise at pump location

Pump Sizing

Proper sizing depends on:

Well depth and water level
Household water demand
Pressure requirements
Pipe diameter and length
Professional sizing recommended

Buying a Home with a Well

Due Diligence Steps

Request well log: Shows depth, yield, construction details
Get water test: Full panel including bacteria, nitrates, arsenic
Inspect system: Professional assessment of pump, tank, pressure
Check records: Previous tests, repairs, maintenance
Verify permit status: Especially for irrigation or large users

Red Flags

No well log on file
Previous water quality issues
Very shallow well (contamination risk)
Multiple wells on property (why?)
Well near septic system or agriculture
Evidence of previous treatment systems

Seller Disclosure

Washington sellers must disclose:

Known well problems
Water quality issues
Treatment systems in use
Shared well agreements
Water rights or permits

Shared Wells

Legal Considerations

In Washington, shared wells (serving 2+ residences) require:

Written agreement between all parties
Clear cost-sharing arrangements
Maintenance responsibility defined
Process for disputes
May require water system approval

Group B Water Systems

Four or more connections or 25+ users require:

DOH approval as Group B public water system
Regular testing and monitoring
Operating permit
Designated water system manager

Drought and Water Conservation

During Droughts

Eastern Washington particularly affected:

Monitor water level in well
Reduce irrigation
Fix leaks promptly
Stagger high-use activities
Consider storage tank

Water Conservation

Low-flow fixtures reduce well pump cycling
Fix leaky faucets and toilets
Efficient irrigation (drip systems)
Drought-tolerant landscaping
Graywater systems (where permitted)

Resources

State Resources

County Health Districts

Water testing services
Local well requirements
Contamination advisories
Decommissioning guidance

Related Guides

Well drilling requires a Washington-licensed well driller. Always verify credentials with the Department of Ecology before hiring. Well water quality is the homeowner's responsibility—test annually.