Plumbing – What might cause water to leak under or behind a bathtub

Options include looking for discoloration on surrounding areas and even putting a paper towel or Kleenex in suspect areas in order to detect a small leak that may not have been sufficient to create noticeable discoloration. Depending on the volume, you may be able to hear dripping in order to help trace the leak. And you may wish to reconsider whether the initial diagnosis was correct or whether the repair was sufficient.

Here are three causes that weren't obvious to us that you may wish to consider:

(1) Around the tub spigot: We had a situation in which we had a leak from a bathroom on the ceiling of the dining room beneath it. We re-caulked the tub and shower surround, did a small test, didn't see any water leaking, and thought we'd taken care of the problem. The next time someone showered the leak reappeared. We eventually figured out that the problem was around the spigot: Water from the shower was hitting the spigot, and because there was not a good seal around the spigot, water was running behind the spigot, down to the floor, and eventually into the dining room below.

(2) The actual copper supply line connections--if you're fortunate enough to have access to them without tearing out the wall: In another house, one with only one floor, we thought we had a leak in our shower pan, but during a remodeling discovered that the hot supply line had not been soldered correctly and water had been squirting out between the wall and eventually out through the brick in the adjoining exterior wall.

(3) Diversion due to insulation: We had another leak that we thought was due to a problem with the flashing between the roof and adjoining siding. After tearing up the roof and the ceiling of the room being damaged, we discovered that the problem a poorly-sealed nail in the roof itself. However, this location was several feet away from where water damage showed up. In this case, the insulation directly below the small leak was sufficient to keep the water from running straight down. Instead it wound around and into another room.

The most common discrepancies in price between tubs, not counting accessories like heaters and jets, are due to four factors: style, depth, build quality and brand. A garden tub will generally cost you more than a simple rectangular built in, and a clawfoot is more expensive still, followed by "custom" installations like non-overflow tubs.

In the same style, the depth of the tub determines the volume and weight of water the tub must hold and therefore the dimensions and thickness of the material. More material == higher cost.

Even in the same style and depth, one maker may build their tub out of cast iron while another uses plastic, or even in the same material, one maker may double the thickness of the tub walls to increase durability and thus longevity (removing a damaged built-in bathtub is no small job; it can even require a full remodel because it requires re-tiling the backsplash).

Lastly, major name brands will command a higher price even if their product is inferior. Jacuzzi, for one, is a trademarked brand name that has apparently rested on its laurels; I was warned away from even their thousand-dollar tubs for quality reasons, but the tubs still cost a grand, cause they're branded with a universally-known name (so much so that people use the brand without knowing it's a brand, similar to "Band-Aid")

As far as actually what to look for, it depends on what you want. For an upstairs bathroom normally used by kids and guests, a standard Kohler, Moen or American Standard acrylic or cast built-in is fine. Cast iron is more durable, and holds the heat of the water well, but it'll be a beast and a half to put in place. For your own master bathroom, you can be pickier. The three brands I mentioned are names I trust, and they make tubs in all shapes, sizes, styles and pricepoints.