How to Install a Drain Pump for a Basement Sink

Installing a drain pump for a basement sink can be a major improvement for homeowners who have below-grade plumbing issues. This allows you to improve drainage without needing extensive excavation. In this guide, we’ll walk you through how to choose the right pump and the installation process, along with important maintenance tips.

You can follow along as This Old House plumbing and heating expert Richard Trethewey demonstrates how to install a drain pump in the video above.

Understanding Basement Sink Drainage

Basement sinks often have drainage challenges because they’re below the main sewer line. Traditional gravity-fed drainage systems may not work in these situations, leading to water backflow and drainage issues.

The Role of Drain Pumps

Drain pumps, also known as laundry tray pumps, actively move water from the sink to the main drainage system, even when the sink is located below the sewer line. Installing a drain pump allows the water to be transported from a basement sink to your home’s main drainage system, preventing backups and clogs.

How Drain Pumps Work

A drain pump operates using a float switch mechanism. When water enters the pump, the float switch activates the pump, which then pushes the water out through the discharge port. This system can typically lift water to 14 feet vertically and has a motor to facilitate the transfer of water for consistent and reliable drainage.

Choosing the Right Drain Pump

Selecting the right drain pump will provide effective water removal and enhance your plumbing system’s lifespan.

Pump Capacity

For larger and frequently used sinks, look for pumps with higher capacities to handle increased water flow. Determine the vertical lift required to move water from the basement sink to the main drainage system. Your pump should also be capable of handling the maximum flow rate of your faucet to avoid overflow or backup issues.

Additional Features

Pumps with built-in check valves can prevent backflow by blocking water that is being pumped out. Consider pumps designed to operate quietly for less noise disturbance, especially if you frequently spend time in your basement or the space above your drainage system.

Choose pumps that allow for a more straightforward cleaning and maintenance process so you can get more out of your drainage system. Most importantly, check that the pump can be easily integrated into your current plumbing setup without too many modifications.

Basement Sink Drain Pump Installation Process

Installing a drain pump for a basement sink involves many steps. While the process requires some plumbing skills, many homeowners with DIY experience can complete this project. Don’t hesitate to consult a professional if you’re unsure about the installation.

Preparing the Sink

1. Basket strainer installation: Begin by installing a new basket strainer in the sink. Roll plumber’s putty between your hands to form a rope and press it against the underside of the basket strainer. Wrap Teflon tape around the threaded portion of the strainer and set it into the drain hole. Attach the rubber gasket, fiber gasket, and O-ring underneath the sink.
2. Threading the pump: Thread the laundry tray pump onto the basket strainer and tighten it with pliers to prevent leaks.
3. Discharge port preparation: Wrap Teflon tape around the discharge port on the side of the pump. Attach a threaded PVC adapter to the port to connect the drain line.

Connecting the Drain Line

1. Extending the drain line: Use PVC pipe and elbows to extend the pump’s drain line out of the sink cabinet.
2. Cutting the existing drainpipe: Use a PVC saw to cut out a section of the existing drainpipe to accommodate the new connection.
3. Joining the drainpipe: Glue a PVC Y-fitting to the drainpipe and join the remaining joint with a no-hub coupling. Dry-fit PVC pipe and fittings from the discharge port to the Y-fitting on the drainpipe, checking that everything is aligned correctly.

Installing Safety Features

Install these attachments to help your pump work effectively and last longer:

1. Check valve: A check valve prevents water from draining back into the sink, protecting the pump from wear.
2. Ball valve: A ball valve controls the water flow, allowing you to match the pump’s discharge rate to the faucet’s flow rate. This helps prevent the pump from turning on and off frequently, which can shorten its lifespan.

Final Assembly and Testing

1. Gluing the PVC parts: Once all components are in place, glue the PVC parts together using PVC primer and cement, checking the joints are secure to prevent leaks.
2. Connecting power: Plug the pump’s power cord into a GFCI-protected outlet to avoid electrical hazards.
3. Testing the system: Turn on the sink’s faucet and observe the pump’s operation. Adjust the ball valve until the pump runs continuously without frequent on-off cycling.

Maintenance and Troubleshooting Sink Drain Pipes

Understanding common issues with sink drain pipes can help you address small issues before they turn into major repairs.

Routine Maintenance

Regularly clean the pump’s intake screen to prevent clogs that can affect pump performance. Check and tighten all connections frequently so there are no leaks or loose fittings. You should also inspect the float switch for proper operation so it can activate the pump when necessary. Test the GCFI outlet protecting the pump so it can continue to provide protection against electrical hazards.

Common Issues and Solutions

There are a few issues that you can usually resolve quickly. If your pump isn’t activating, check that the power supply is plugged in and the float switch is not stuck or damaged. Weak water flow may be due to a clogged intake screen or pipe obstructions, so you should check for any blockages in the pipes.

Noise can be a result of loose fittings or improper mounting, so you should tighten them and check that the pump is securely mounted. If you notice the pump cycles on and off frequently, adjust the ball valve to match the water inflow and outflow rates. This prevents the pump from short cycling, which can cause damage over time.

Monitoring and Replacement

In addition to routine maintenance, you should monitor the performance of your drain pump system. Pay attention to changes in noise, water flow, or pump activation, which could indicate underlying issues. If you notice problems that maintenance can’t resolve, it may be time to consider replacing the pump or its components. Regular monitoring can help you detect issues early on and address them before they become bigger problems.