Check Valves
Updated February 24, 2026
Allow water to flow in one direction only, preventing backflow. Essential for protecting water supply from contamination. Typical price range: $10 – $80. Best for: Sump pump discharge, irrigation, backflow prevention.
Overview
Check valves allow water to flow in one direction only. When flow reverses, the valve closes automatically. No handle, no manual operation -- purely mechanical, activated by water pressure and gravity. Essential for preventing backflow in sump pump discharge lines, water heater recirculation loops, booster pump outlets, and anywhere cross-contamination must be prevented. Spring-loaded, swing, and inline are the three main residential types.
How to Choose Check Valves
Check Valves are best suited for sump pump discharge, irrigation, backflow prevention. They typically cost $10 – $80, so plan your budget accordingly. Sizing is important — match the check valve size to the pipe: 1-1/2 inch for sump pump discharge, 3/4 inch for water heater recirculation, 1 i... Key advantages include prevents backflow and automatic operation.
Pros & Cons
- Prevents backflow
- Automatic operation
- No external power needed
- Creates slight pressure drop
- Can cause water hammer
- Needs regular inspection
Key Features
- Automatic one-way flow -- no manual operation required
- Prevents backflow and cross-contamination of water supply
- Spring-loaded: works in any orientation, positive closure
- Swing check: gravity-assisted, lower pressure drop, horizontal or vertical (flow-up) only
- Inline (disc): compact, fits tight spaces, moderate pressure drop
Top Brands for Check Valves
Sizing & Selection
Match the check valve size to the pipe: 1-1/2 inch for sump pump discharge, 3/4 inch for water heater recirculation, 1 inch for main backflow prevention. The valve must be rated for the system pressure and flow rate. Oversized check valves may not close reliably at low flow rates.
Installation
Sump pump discharge: install vertically on the discharge pipe above the pump, arrow pointing up (direction of flow). Recirculation: install at the water heater return line. Backflow prevention: install per local code requirements (may require a certified backflow device instead of a simple check valve). Orientation matters -- the arrow on the valve body indicates flow direction.
Maintenance
- Check valves fail by sticking open (backflow occurs) or sticking closed (no flow).
- Test annually by shutting off the pump or supply and listening for backflow through the valve.
- Sump pump check valves: if the pump short-cycles, the check valve may be stuck open -- water flows back into the pit after each cycle.
- Replace every 5-7 years as preventive maintenance. A failed check valve on a sump pump means the pump works twice as hard.
Buying Tips
- Spring-loaded check valves (-25) are the most reliable for residential sump pump and recirculation applications.
- Brass or stainless steel for potable water. PVC for sump pump discharge and drainage.
- Quiet check valves (spring-loaded with soft closure) prevent the loud clank when the valve closes. Worth the premium if the pump is near living space.
- For backflow prevention on irrigation or commercial connections, local code may require a certified reduced pressure backflow assembly (RPZ) instead of a simple check valve. Check with your water utility.
Frequently Asked Questions
What are the advantages of check valves?
Prevents backflow Automatic operation No external power needed
What are the disadvantages of check valves?
Creates slight pressure drop Can cause water hammer Needs regular inspection
Who should buy check valves?
Check Valves are best for: Sump pump discharge, irrigation, backflow prevention.
How are check valves installed?
Sump pump discharge: install vertically on the discharge pipe above the pump, arrow pointing up (direction of flow). Recirculation: install at the water heater return line. Backflow prevention: install per local code requirements (may require a certified backflow device instead of a simple check valve). Orientation matters -- the arrow on the valve body indicates flow direction.
How do I choose the right size for check valves?
Match the check valve size to the pipe: 1-1/2 inch for sump pump discharge, 3/4 inch for water heater recirculation, 1 inch for main backflow prevention. The valve must be rated for the system pressure and flow rate. Oversized check valves may not close reliably at low flow rates.
What are the best brands for check valves?
Top brands for check valves include Apollo, Bell & Gossett, BrassCraft, Caleffi. Each offers different price tiers and product lines.
How do I maintain check valves?
Key maintenance tips: Check valves fail by sticking open (backflow occurs) or sticking closed (no flow).. Test annually by shutting off the pump or supply and listening for backflow through the valve.. Sump pump check valves: if the pump short-cycles, the check valve may be stuck open -- water flows back into the pit after each cycle..