How to Install an RV Shower Drain: Easy Step-by-Step Guide

Installing a new RV shower drain might seem like a daunting task, but it is one of the most rewarding DIY projects for any RVer. A properly installed drain ensures that your shower function operates smoothly, prevents costly water damage to your vehicle's interior, and maintains the structural integrity of your bathroom floor. This guide walks you through the entire process, from selecting the right components to sealing the final connection.

Before you begin, it is crucial to understand the two primary types of drains available: standard drains and low-profile drains. Standard drains are the most common and are designed to sit below the floor level, requiring a deeper ceiling cavity. Low-profile drains, on the other hand, sit almost flush with the subfloor, making them ideal for campers with limited overhead space. Choosing the correct type based on your RV's specific architecture is the first step toward a successful installation.

Preparing Your Tools and Materials

Gathering the right tools before starting cannot be overstated. Working in a confined space like an RV shower requires efficiency, and having everything at your fingertips saves time and frustration. You will need a comprehensive set that includes channel-type pliers, a utility knife, a drill with various bits, a jigsaw or rotary tool, and a tape measure. Additionally, having a flashlight and a small mirror on hand will help you see tight corners without dismantling large sections of your wall.

• New RV shower drain kit (core component)
• Screwdriver set (Phillips and flathead)
• Plumber's putty or silicone sealant
• Hacksaw or PVC cutter
• Fine-grit sandpaper
• Rags and cleaning solution

Removing the Old Drain Assembly

If you are replacing an existing drain, the first step is to remove the old assembly. Start by loosening the locknut located beneath the shower floor. You will likely need channel-type pliers for this, as these nuts can become corroded over time. Once the nut is loose, carefully lift the drain strainer from the floor, being mindful of any debris that might fall into the P-trap below. It is highly recommended to place a bucket or towel underneath to catch any residual water.

With the old drain removed, inspect the condition of the floor around the drain hole. Look for any signs of soft wood or water damage; this is your opportunity to address any rot before installing the new hardware. If the subfloor is compromised, you will need to cut out the damaged section and replace it with new plywood before proceeding. Skipping this step will lead to instability and leaks down the line.

Measuring and Cutting the Hole

Accuracy in this phase is the difference between a tight fit and a messy rework. Most standard drain kits require a specific hole size, which is usually outlined in the instructions. Use a tape measure to find the center of the drain location, ensuring it is positioned correctly for the drain flange to sit flat against the subfloor. Mark the dimensions carefully using a pencil.

Using a drill, create a pilot hole to insert your jigsaw or rotary tool. Slowly cut along the marked lines, taking care not to rush the process. If you are cutting too fast, you risk splintering the floor. Once the hole is cut, test the fit of the new drain body. It should slide in smoothly without requiring excessive force. If the hole is too small, gently expand it; if it is too large, you will need to patch the area and start again.

Installing the Drain Components

With the hole perfectly sized, you can now assemble the drain body. Most kits consist of a drain strainer, a rubber gasket, a locknut, and the main drain pipe. Begin by applying a generous amount of plumber's putty to the underside of the strainer. This creates a watertight seal that prevents moisture from seeping between the drain and the shower floor.

Insert the strainer into the hole from the top and align it properly. From beneath the floor, slide the rubber gasket into place, followed by the locknut. Use your pliers to tighten the nut securely, but do not overtighten, as this can crack the plastic components or the surrounding wood. The goal is firm resistance that prevents wobble without stressing the materials.

Connecting the P-Trap and Final Sealing

The final mechanical step involves connecting the P-trap assembly. This curved pipe holds water to prevent sewer gases from entering the shower, and it must be aligned carefully to ensure proper drainage. Hand-tighten the slip nuts that connect the trap to the drain body, then use your channel locks to secure them firmly. Remember, the pipes do not need to be excessively tight; hand-tight plus a quarter turn is sufficient to prevent leaks.

Before restoring water pressure, you must address the ceiling penetration. Where the drain pipe exits the shower floor and enters the living space below, apply a high-quality silicone sealant. Smooth the edges with a damp finger to ensure a seamless barrier. This step is vital for preventing condensation and vapor leaks that could damage your cabinetry or interior walls. Once the sealant cures, run water through the shower for several minutes to check for any drips or pooling, ensuring your installation is complete and leak-free.