How to Fix a Leaking Bathtub

Close up of faucet and bathtub in modern bathroom
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Because bathtubs, with or without integrated showers, get such frequent use and the amounts of water used are quite copious, any type of bathtub leak can be an annoying and potentially very serious problem. Left untreated, some leaks can cause literally thousands of dollars in damage, requiring major repairs and renovations.

Drain Leaks vs. Faucet Leaks vs. Grout/ Caulk Leaks

Most bathtubs leaks can be categorized as one of three types:

  • Drain leaks. The drain fitting in the bottom of the tub, or in the surrounding drain and drain-trap piping, may loosen, causing dripping leaks, usually in the space beneath the bathtub. These can be quite serious, since the water may be somewhat hidden and can cause serious damage and wood rot before it is even spotted. Because they are slow, gradual leaks, a considerable amount of damage can occur before such leaks are spotted.
  • Faucet leaks. The various water supply components, including the faucet valve, the faucet spout, the shower head, or the water supply connections in the wall, may develop leaks. Dripping faucet or shower head leaks are usually not terribly serious, since the water simply goes down the bathtub drain, but they can waste an enormous amount of water. These leaks are usually fairly easy for DIYers to repair themselves. But leaking water supply pipes inside the walls are much more serious, since they can damage wood and ceiling surfaces below the tub.
  • Grout and caulk leaks. One of the most common types of leaking occurs when the mortar grout lines or the caulking between a bathtub/ shower and the walls develop cracks or gaps. Gradually, water from the shower head or splashing water in the tub can infiltrate through the walls into stud cavities behind the wall surface. Mold, rot, and other problems can gradually take hold, and by the time you spot the damage, the needed repairs may involve very expensive renovation. Spotted early, though, correcting these problems and preventing future issues is quite easy.

    Correcting Drain Leaks

    Drain line leaks may be largely invisible, until you see discoloration in the ceiling below a second-story bathroom, or the tub begins to flex and sag because the subfloor has begun to rot. Fixing bathtub drain leaks can involve one of three types of repairs:

    • Fixing the connection where the overflow tube connects to the tub and drain pipe in the wall. If this overflow cover becomes loose, the problem can often be fixed merely by tightening the overflow cover on the tub, or replacing the rubber gasket that seals the cover against the surface of the tub.
    • Inspecting and tightening the slip-joint connections on the drain-trap beneath the tub. This is not hard to do, but it does require having access to the space beneath the tub. A properly installed bathtub will have an access panel in the wall behind the bathtub—such as in a closet or room adjacent to the bathroom. With some alcove bathtubs, the front panel of the tub may be removable to provide access to the drain fittings. If you have access, repairs are simply a matter of inspecting and tightening the drain trap fittings so they do not leak. If the drain trap fittings are quite old, this may mean replacing them with a new drain trap unit.
    • Repairing or replacing the bathtub drain fitting. Bathtub drains are sealed in place with rubber gasket beneath the tub, with another gasket or plumber's putty used to seal the top of the drain flange where it fits against the inside of the drain opening. If the gaskets or putty break down, the tub drain may leak into the space below the bathtub. Replacing the drain fitting is a somewhat complicated job, but it is well within the skill level of most DIYers, especially if there is access to the space.

      Correcting Faucet and Water Supply Leaks

      Some faucet and water supply leaks can tackled at your leisure, while other require emergency haste. It all depends on the nature of the leak.

      A simple dripping faucet or shower head usually just means that the internal seals on the faucet valve have worn out.This requires nothing more than replacing the faucet cartridge or rubber washers or seals. It is among the easiest of DIY projects.

      Much more urgent is when the pressurized water supply pipes in the walls have developed leaks. Here, spraying water may put large amounts of water into the wall in a short amount of time, leading to very expensive damage. Here, the solution is to turn off the water supply immediately, then inspect and repair or replace any leaking fittings or pipes that are discovered. This can often occur when a water supply system is reaching the end of its useful life, and it may indicate that large sections of pipe or even the entire system needs to be replaced. For example, this kind of leaking may indicate that old galvanized steel water supply pipes need to be replaced with all-new copper or PEX piping. Here is an instance where most homeowners call in a professional plumber for evaluations and installation of new plumbing.

      Fixing Grout and Caulk Leaks

      Some leaks have nothing to do with either the drain pipes or the faucet/water supply pipes. In a bathtub with a shower and tiled walls, it is quite common for cracks to develop in the mortared grout lines between tiles. Splashing, running water from the shower can seep into and through the walls, causing the backer material to soften and decay, and sometimes causing rot to the studs in the wall. Over time, serious mold problems can develop inside walls if this leaking is not addressed.

      In addition to grout lines, bathtubs are sealed along the seams where the top of the tub meets the wall. If the caulk that seals this seam becomes cracked or loose, splashing water can also enter the walls through cracks.

      Both problems can be very easily prevented simply by regularly inspecting grout lines and caulk joints and regrouting or recaulking whenever cracks or openings develop. If water has been allowed to seep into the wall for some time, the repairs can be more major, involving removing wall surfaces, repairing any damage to the backer material and wall studs, then rebuilding and retiling the walls. Here is one instance where an ounce of prevention is worth a ton of cure.

      Bathtub Liners?

      Much less commonly, a bathtub may develop actual cracks or holes in the body of the tub, with water leakage occurring directly through the sides or body of the tub, into wall or floor spaces. This is most common in cheap fiberglass or acrylic tubs, and is virtually unheard of in porcelain or steel-enameled tubs.

      The most logical repair in such a situation is to replace the entire bathtub with a new unit. Where this is financially impossible, it is also possible to install a bathtub/shower liner. These liners are carefully sized and fabricated shells that slip in place directly over the old tub/shower unit, forming a perfectly water-tight surface that can give the look of a perfectly new bathtub (at least initially). But bathtub liners aren't cheap, often costing as much as $3,000 for a professionally sized and fabricated unit. And a liner may not be a permanent solution, since they are relatively thin shells that may wear out and crack within a few years.