What is the backflow valve in the basement floor?

A backflow valve in the basement floor is an important plumbing fixture that prevents contaminated water from flowing back into the drinking water supply. Installing a backflow valve helps protect your home’s water quality and prevents potential health hazards.

What is a backflow valve?

A backflow valve, also known as a backflow preventer, is a mechanical plumbing device that allows water to flow in only one direction. Its purpose is to prevent backflow, which is when water flows in the opposite direction from its intended path.

There are several types of backflow valves used in plumbing systems:

• Check valve – A simple mechanical valve that uses a disc, flap, or spring to allow water to flow in one direction but closes to prevent reverse flow.
• Atmospheric vacuum breaker – Contains a float disc that seals off the water supply if a drop in pressure is detected.
• Pressure vacuum breaker – Similar to an atmospheric vacuum breaker but can operate under constant pressure.
• Reduced pressure zone backflow preventer – Consists of springs, checks and relief valves to protect against backflow from backsiphonage or backpressure.

Backflow preventers are commonly installed on water lines supplying areas where contamination could potentially occur if water flowed backwards. This includes irrigation systems, boilers, fire sprinkler systems, and outlets with hose attachments.

Why install a backflow valve in the basement floor?

There are a few key reasons why a backflow valve may be installed in the basement floor drain:

• Protect the public water supply – Preventing backflow into the main water lines helps prevent contaminants from entering the public water system and affecting other homes.
• Prevent sewage backflow – Sewage can back up into the basement during heavy rains or sewer line blockages. A backflow valve prevents sewage from flowing backwards into the home’s water pipes.
• Protect appliances – Water that backflows into appliances like hot water heaters and boilers can cause internal corrosion and contamination.
• Required by code – Many municipalities require backflow valves in high hazard installations like fire sprinkler systems and irrigation systems.

While less common than installing backflow valves on water lines, adding one to the basement floor drain provides an added layer of protection by preventing the rare occurrence of sewage or contaminated groundwater from entering the home through the floor drain.

How does a basement floor drain backflow valve work?

A backflow valve installed in a basement floor drain operates automatically to prevent reverse flow. Here is how it works:

• Flow in normal direction – When water flows down through the drain in the normal direction, the valve remains open allowing water to drain.
• Flow stops – When water stops flowing, the valve’s disc, flap, or mechanism closes off the opening.
• Reverse flow – If water attempts to flow backwards up through the drain, the backflow valve remains closed, blocking reverse flow.
• Forward flow resumes – When water flows down in the normal direction again, the valve opens to allow draining.

This automatic opening and closing during normal operation prevents any backflow through the basement floor drain while still allowing the drain to function properly.

Types of backflow valves for basement floor drains

Two common types of backflow valves used for basement floor drain applications include:

Swing Check Valve

• Simple mechanical flap or disc that swings shut to prevent reverse flow.
• Allows full forward flow and passive reverse flow blocking.
• Prone to jamming by debris. Should be installed horizontally.
• Inexpensive check valve option.

Spring Check Valve

• Uses a spring to firmly close the valve disc and prevent backflow.
• Withstands higher backpressure than a swing check.
• More resistant to jamming and debris.
• Can be installed vertically or horizontally.
• More expensive but higher performance.

The spring check valve is generally the preferred option due to its durability and performance in preventing backflow.

How to install a backflow valve in a basement floor drain

Proper installation is important for a backflow valve to function properly. Here are the key steps:

1. Turn off main water supply and drain all pipes.
2. Remove existing drain pipe and clean the drain opening thoroughly.
3. Apply pipe primer and cement to valve and pipe ends.
4. Glue valve directly into drain opening if possible.
5. If drain opening is too large, glue a size-reducing fitting first to fit valve.
6. Ensure valve is oriented in the correct direction with flow arrow pointing down.
7. Attach drain pipe into outlet end of valve.
8. Allow cement to fully cure before turning water back on.
9. Test for leaks and proper operation when water service is restored.

The valve should be positioned horizontally for optimal functioning. While this project can be DIY, hiring a professional plumber is recommended to ensure proper installation.

Maintenance of basement floor drain backflow valves

Like any plumbing fixture, backflow valves require periodic maintenance to keep them working properly. Recommended maintenance includes:

• Inspecting visually for signs of wear or leaks – Quarterly
• Testing water flow in both directions – Annually
• Cleaning out any debris which may get lodged – As needed
• Confirming drain line is free of clogs – Annually
• Testing relief valve on spring check valves – Annually
• Repairing or replacing worn or damaged valves – As needed

Replacing valves approximately every 5-10 years is recommended for optimal performance.

Costs of installing a backflow valve

Typical costs for installing a backflow valve in a basement floor drain include:

Component	Cost
Backflow valve	$20 – $200 depending on type of valve
Size-reducing fittings, primer & cement	$20 – $50
Plumber hourly rate	$45 – $150 per hour
Total installation cost	$200 – $500, excluding new drain pipe if needed

This relatively inexpensive plumbing upgrade can provide peace of mind by adding an important layer of protection from backflow contamination.

Conclusion

Installing a backflow prevention valve on the basement floor drain is an easy and affordable way to prevent contaminated water from backing up into the home’s water supply. While not always required, it provides inexpensive insurance against health hazards like sewage backflow. A simple spring check valve installed properly can last for many years with periodic maintenance. Considering the minimal cost compared to the benefits, a basement floor drain backflow valve is a smart investment in protecting your home’s water quality and safety.