If you’ve ever wondered how to prevent water from flowing backward in your pipes, you need a non-return valve (also called a check valve or one-way valve). Today, we’ll focus on 15mm non-return valves – one of the most popular sizes for home and small business use.
For complete selection guidelines and cross-reference documentation on this product line, please consult our directional control valve troubleshooting guide.
What is a 15mm Non-Return Valve?
A 15mm non-return valve is a small but mighty device that allows water or other fluids to flow in only one direction. Think of it like a door that only swings one way – when water tries to flow backward, the valve automatically closes to stop it.
Why the 15mm size matters:
- Perfect for standard home plumbing (fits 1/2 inch pipes)
- Handles up to 36 liters per minute
- Compact enough for tight spaces
- Most common size for residential use
Key Benefits
Prevents backflow – Stops contaminated water from mixing with clean water
Protects equipment – Keeps pumps and water heaters safe from reverse flow
Saves money – Prevents costly system damage
Easy to install – Simple DIY project for most homeowners
How Does a Non-Return Valve Work?
The science behind these valves is surprisingly simple:
1
When water flows forward: The valve opens automatically due to water pressure
2
When water tries to flow backward: The valve closes tight, creating a seal
3
No power needed: Works purely on water pressure and gravity
Most 15mm valves open when water pressure reaches just 0.1 to 0.15 bar – that’s very little pressure, about the same as water flowing from a height of 3 feet.
Types of 15mm Non-Return Valves
Not all non-return valves are created equal. Here are the main types you’ll find:
1. Swing Check Valves
How they work: A hinged flap swings open and closed
Best for: Basic home plumbing, low-pressure systems
Pros: Cheap, simple, easy to install
Cons: Slower response time
Price range: $8-20
2. Spring Check Valves
How they work: A spring pushes a disc to open and close
Best for: Pump outlets, systems with changing pressure
Pros: Fast response, reliable, adjustable opening pressure
Cons: Spring can wear out over time
Price range: $12-25
3. Ball Check Valves
How they work: A ball rolls to block or allow flow
Best for: Washing machines, hot water systems
Pros: Easy to maintain, very reliable seal
Cons: Needs minimum water pressure to work
Price range: $10-22
4. Dual Plate Valves
How they work: Two plates flip open like butterfly wings
Best for: High-flow applications, tight spaces
Pros: Lowest pressure loss, very fast action
Cons: More expensive
Price range: $15-35
Technical Specifications You Should Know
When shopping for a 15mm non-return valve, here are the key specs to look for:
| Specification | Typical Range | What It Means |
|---|---|---|
| Maximum Pressure | 12-25 bar | How much pressure the valve can handle |
| Flow Rate | Up to 36 L/min | How much water can pass through |
| Temperature Range | -20°C to +110°C | Safe operating temperatures |
| Opening Pressure | 1.7-2.1 kPa | Minimum pressure needed to open |
| Connection Type | BSP threads | How it connects to your pipes |
Material Options
Brass (Most Popular)
- Great for drinking water
- Resists corrosion
- Affordable ($8-20)
- Perfect for home use
Stainless Steel
- Industrial strength
- Handles high temperatures
- More expensive ($15-35)
- Best for commercial use
Plastic (PVC/PP)
- Lightweight and cheap ($5-12)
- Good for chemical applications
- Lower pressure rating
- Not suitable for hot water
Where to Use 15mm Non-Return Valves
Home Applications
- Hot water systems – Prevents cold water from backing into hot water lines
- Washing machines – Stops dirty water from contaminating clean water supply
- Garden irrigation – Prevents soil contamination of drinking water
- Water pumps – Protects pump from damage
Commercial Uses
- Building water systems – Prevents cross-contamination
- Industrial processes – Controls flow direction in manufacturing
- Fire protection systems – Maintains water pressure in emergency systems
Installation Guide: Step by Step
Tools You’ll Need:
- Adjustable wrench
- PTFE tape (thread sealant)
- Pipe cutter (if needed)
Installation Steps:
1
Turn off water supply – Always start with water off!
2
Choose the right location – Install as close as possible to the equipment you’re protecting
3
Check flow direction – Look for the arrow on the valve body – this shows which way water should flow
4
Prepare the pipes – Clean threads and apply PTFE tape
5
Install the valve – Hand-tighten first, then use wrench to secure (don’t over-tighten!)
6
Test the system – Turn water back on slowly and check for leaks
- Install horizontally when possible for best performance
- Leave space around the valve for future maintenance
- Consider a union-type valve for easier removal later
Maintenance and Troubleshooting
Regular Maintenance (Every 6-12 Months)
- Check for leaks around the valve
- Test that water flows freely in the correct direction
- Listen for unusual noises that might indicate problems
Common Problems and Solutions
Problem: Valve won’t open
Solution: Check for debris blocking the mechanism. Clean or replace if necessary.
Problem: Water leaking around the valve
Solution: Tighten connections or replace worn seals.
Problem: Valve chattering or making noise
Solution: Usually means the valve is too big for the flow rate. Consider a smaller valve or install a flow restrictor.
Problem: Valve sticking in open position
Solution: Debris or mineral buildup. Remove and clean the valve internals.
Top Brands and Where to Buy
Recommended Brands
Watts APEX
(Premium Choice)
- Excellent build quality
- WRAS certified for drinking water
- Price: $12-18
- Available at: Professional plumbing suppliers
Flomasta
(Best Value)
- WRAS approved
- Easy to find in stores
- Price: $8-15
- Available at: B&Q, major home improvement stores
RS PRO
(Industrial Grade)
- Heavy-duty construction
- Long warranty
- Price: $15-25
- Available at: RS Online, industrial suppliers
Brymec
(Reliable Middle Ground)
- Good balance of price and quality
- WRAS certified
- Price: $10-18
- Available at: Online plumbing retailers
Where to Shop
- Home improvement stores: B&Q, Home Depot, Lowe’s
- Online retailers: Amazon, specialized plumbing sites
- Trade suppliers: For professional-grade valves
- Local plumbing stores: Often have expert advice
Buying Tips: What to Look For
Essential Features
Certification marks – Look for WRAS, NSF, or other water safety approvals
Pressure rating – Make sure it exceeds your system pressure
Temperature rating – Consider your hottest water temperature
Union connections – Makes future maintenance much easier
Red Flags to Avoid
No certification marks – Could be unsafe for drinking water
Unusually cheap prices – Quality issues likely
No flow direction arrow – Sign of poor manufacturing
Limited warranty – Manufacturer doesn’t stand behind product
Cost Analysis: What Should You Expect to Pay?
| Quality Level | Price Range | Best For | Expected Lifespan |
|---|---|---|---|
| Budget | $5-10 | Basic applications, non-critical systems | 2-5 years |
| Mid-range | $10-20 | Home plumbing, most applications | 5-8 years |
| Premium | $20-35 | Commercial use, high-reliability needs | 8-15 years |
Money-saving tip: It’s usually better to buy one good valve than to replace cheap ones multiple times.
Frequently Asked Questions
Q: Can I install a 15mm non-return valve myself?
A: Yes! It’s a straightforward job for most DIYers. Just remember to turn off the water first and don’t over-tighten.
Q: How do I know if my valve is working?
A: The easiest test is to disconnect the pipe downstream and see if water flows backward when you turn off the supply. No backflow = working valve.
Q: How long do non-return valves last?
A: With proper installation and maintenance, a good quality valve should last 5-10 years in typical home use.
Q: Do I need a plumber to install one?
A: Not usually, but if you’re not comfortable working with plumbing or if the installation requires cutting into main supply lines, it’s worth hiring a professional.
Q: Can I use a 15mm valve on a 1/2 inch pipe?
A: Yes! 15mm and 1/2 inch are essentially the same size in plumbing terms.
Conclusion: Making the Right Choice
Protect Your Plumbing Investment Today
A 15mm non-return valve is a small investment that can save you from big problems. Whether you’re protecting your home’s water supply, keeping your washing machine from contaminating your drinking water, or safeguarding expensive equipment, the right valve makes all the difference.