Check valves are fundamental components in plumbing, but many people only hear about them when a problem arises - such as water backflow, bad smells or even flooding. Despite their small size, they play an essential role in protecting the plumbing system.
In this comprehensive guide we explain what a check valve is, how it works, where it should be installed, the main types available and why installing one can prevent serious damage. For professional installation and checking, the Lisbon plumber company is the best solution for guaranteeing the safety and proper functioning of the system.
What is a check valve?
A check valve is a device that allows water or fluid to flow in one direction only. When the flow tries to reverse, the valve closes automatically, preventing the flow from returning.
In simple terms: it works like an “automatic door” that only opens one way.
Why are check valves important?
Without a check valve, various problems can occur:
- Dirty water flows back down the drain
- Contamination of drinking water
- Flooding in the event of a blockage in the public network
- Pressure loss in the system
- Damage to equipment such as water heaters and pumps
In areas where there is a risk of blockage or an overloaded sewer, a non-return valve can prevent extremely unpleasant situations.
How does a check valve work?
The operation is simple:
- When the water flows in the right direction, the valve opens.
- When the flow tries to reverse, the pressure automatically closes the mechanism.
Closing can be done using:
- Swinging hatch
- Inner spring
- Inner ball
- Articulated disk
Most common types of check valves
1. Gate check valve (clapper)
It uses a flap that opens with the flow and closes when there is a return.
2. Spring-loaded check valve
It has an internal spring that ensures quick and secure closure.
3. Ball check valve
An internal sphere blocks the return flow.
4. Non-return check valve for sewers
Installed in drainage systems to prevent waste water from flowing back into the house.
Where are check valves installed?
- At the water inlet
- In pumping systems
- At the outlet of water heaters
- In water columns
- In the sewage system
- In irrigation systems
When is installation mandatory?
In many modern systems, especially in buildings, the installation of non-return valves is recommended or required to protect the public network from contamination.
For general technical guidelines on hydraulic infrastructures and safety, you can consult information provided by National Civil Engineering Laboratory.
Signs that the check valve may be faulty
- Bad smell from drains
- Return of dirty water
- Unusual noises in the pipe
- Unexplained pressure loss
- Flooding during heavy rains
If the valve is blocked or damaged, it may no longer protect the system.
Check valve maintenance
Although many valves work for years without intervention, it is recommended:
- Periodic inspection
- Cleaning up in case of residue build-up
- Replacement if there is wear or corrosion
Common installation errors
- Installing in the wrong direction
- Use an unsuitable model for the system
- Ignoring the need for maintenance
- No access for future inspection
Why choose Lisbon Plumber
A Lisbon Plumber company installs and replaces check valves, ensuring that the system functions correctly and is protected against unwanted returns.
- Complete technical diagnosis
- Choosing the right model
- Safe and standardized installation
- Pressure and function check
- Service in and around Lisbon
Conclusion
Check valves are small but essential for preventing backflow, contamination and structural damage. Installing them correctly increases plumbing safety and reduces the risk of future problems.
If you want to install or check a check valve in your home or building, Lisbon Plumber can help with a professional assessment and appropriate intervention.
