Kitchen & Bath: Basement Bathroom Retrofit

By: Jim Eggert

Download PDF version (370.9k) Log In or Register to view the full article as a PDF document.

Tying In The basin requires a 2- to 4-inch tee-wye connection, cut into the existing sewer or septic line, with a check valve on the ejection side to prevent refilling of the basin (Figure 2).

Figure 2. The sump basin receives wastewater from bathroom fixtures. The grinder pump liquifies the sewage and pumps it up to the main drain line exiting the house. A check valve prevents gravity backflow into the basin. For the piping above the basin, Schedule-40 PVC provides a quick and simple tie-in. In my experience, sometimes the pump will create excessive vibration in the piping. In these cases, installing a Fernco or Mission flexible connector in the line will absorb the vibration and prevent stress from building up at the rigid connections. This fitting also serves as an easy disconnect should the basin require servicing. As with any plumbing drain, venting is important. Without a vent in the sump basin, the pump action would create a powerful vacuum. The basin includes a vent connector, either molded into the lid or the body of the basin, which eliminates the need to disconnect the vent pipe when removing the lid. The inlet pipe from the bathroom fixtures connects to the basin inlet connector, completing the drainage installation. Once this connection is made, I backfill the excavated areas with sand or gravel and repair the concrete surface. I take extra care with the patching process, making sure that the floor is restored to a flush, smooth condition. Any lumpiness in the floor finish will telegraph through carpet or vinyl flooring.

Finishing Up

After the bathroom walls are framed, my plumber completes the rest of the rough plumbing above the floor just like any installation. Tying the fixture vents back into the main stack finishes the drain job. The ejector pump can be either hard-wired or have an integral plug, so I have my electrician wire a connection near the tank location, and the system is operational (Figure 3).

Figure 3. Only the top of the basin shows, allowing service access. Plug-in power simplifies the disconnect.

An option you may want to add is an alarm system, which monitors the basin level. An integral float furnished with the pump provides automatic on-and-off action, in response to usage. In case the pump does not cycle, an audible alarm sounds to warn against usage until the system is checked. Few manufacturers supply these alarms as part of their package, but I feel it’s a worthwhile investment for both the customer and the contractor. Both battery and electric alarm models are available. Line-voltage alarms should not be plugged into the same circuit as the pump, because if the pump has failed due to an electrical fault in that circuit, the alarm should still function. Alarm costs vary, but average about $50. I highly recommend their use, especially if children are going to use the new bathroom. Ejector pump prices currently start at about $625 for self-contained systems and $325 for an in-floor setup. They are available from plumbing supply houses and some larger home centers. Jim Eggert owns and operates Eggert Construction, providing design/build services in Branford, Conn.