A well yield test measures how much water your well can sustainably produce, typically expressed in gallons per minute (GPM). This critical information is needed for real estate transactions, building permits, pump sizing, and understanding your well's capability.
When You Need a Well Yield Test
- Buying property: Know what you're getting before purchase
- Selling property: Buyers and lenders often require it
- Building permits: Many counties require proof of adequate water
- Pump sizing: Right-size your pump system
- Diagnosing problems: Compare current yield to original
- Irrigation planning: Know if well can support agricultural use
Types of Yield Tests
Standard Yield Test
Most common test for residential wells. Measures flow rate over 1-4 hours.
- Duration: 1-4 hours
- Cost: $200-$400
- Best for: Real estate transactions, general assessment
Extended Pump Test
Longer test provides more data about sustainable yield.
- Duration: 4-24 hours
- Cost: $400-$800
- Best for: Agricultural wells, high-capacity needs, permit requirements
The Testing Process
- Measure static water level: Water level at rest, before pumping
- Pump at controlled rate: Extract water at known GPM
- Monitor drawdown: Track how water level drops during pumping
- Calculate sustainable yield: Determine long-term production capacity
- Measure recovery: How quickly water level rebounds after pumping stops
Understanding Results
| Yield (GPM) | Assessment | Suitable For |
|---|---|---|
| Under 1 GPM | Very low | May need storage tank or new well |
| 1-3 GPM | Low but usable | Small household with storage |
| 3-5 GPM | Adequate | Typical household |
| 5-10 GPM | Good | Larger household, some irrigation |
| 10-20 GPM | Very good | Large household + irrigation |
| 20+ GPM | Excellent | Agricultural/commercial use |
What the Report Includes
- Static water level
- Pumping water level (drawdown)
- Flow rate in GPM
- Recovery rate
- Calculated sustainable yield
- Recommendations
Yield Test vs. Flow Test
Flow test: Quick measurement of current pump output. Takes minutes.
Yield test: Comprehensive assessment of well capacity. Takes hours, provides sustainable yield data.
Need Professional Help?
Southern California Well Service is here for all your well needs. Licensed, insured, and trusted.
(760) 440-8520Serving San Diego, Riverside & San Bernardino Counties
