A bath usually drains slowly because hair and soap have built up in the plug fitting, the waste or the trap underneath. It can also happen when a pop-up or click-clack plug no longer opens fully, or when the waste pipe has too little fall, so water does not run away freely.
One slow bath is often a local problem. If other fittings are slow at the same time, the cause may be further along the drain.
Hair, Soap and the Plug Fitting
Hair mixes with soap, shampoo and bath products to form a sticky mat. It often collects around the plug and the moving parts beneath it, where it is hard to see.
Many baths have a click-clack plug that you press to open and close, or a pop-up plug worked by a handle on the overflow. If the mechanism is worn or out of adjustment, the plug may only lift a little, which restricts the flow even without a blockage.
A simple plughole hair catcher can help reduce build-up from day to day.
The overflow can collect grime too. On pop-up wastes, the linkage that runs from the overflow handle down to the plug sits in the water path and can gather hair along its length.
The Trap and Waste Pipe
Under the bath, a trap holds a small amount of water to stop smells. Debris can settle in it over time and slow the flow.
The waste pipe needs a steady downward slope to the wall or drain. If it runs too flat, sags between supports or has many bends, water can drain slowly and debris is more likely to settle. This kind of problem tends to return even after cleaning.
Bath traps are often hard to reach behind the panel, so they tend to be cleaned less often than a sink trap.
What Different Signs May Mean
A bath that has slowed gradually over months often points to a build-up in the waste or trap. A sudden change may suggest something has dropped into the plughole or the plug mechanism has slipped.
Gurgling from the bath when a nearby basin or toilet is used, or a slow shower and basin at the same time, may point to a shared waste pipe or drain. These signs do not prove a drain problem, but they suggest the cause may lie beyond the bath.
What to Avoid and When to Get Help
Avoid pouring strong drain cleaners into the bath. They can damage acrylic surfaces and some fittings, and mixing different products can give off harmful fumes. Do not push wires or sharp tools into the waste, as you could damage the trap or the bath finish.
If the bath stays slow after clearing the hair you can reach, the problem may be under the panel. Our Oxford bath plumbing visits can check the plug mechanism, waste, trap and pipe, and put right whatever is holding the water back.