Plenty of household plumbing is reasonable to attempt. A few specific things regularly turn a small problem into an expensive one.
Overtightening is the most common. Plumbing fittings seal through a washer, a thread seal or an olive, not through force. Overtightening cracks fittings, distorts seals and strips threads, and the resulting leak is usually worse than the original problem.
Chemical drain cleaners are the second. They rarely resolve anything structural, they can damage older pipework, and they leave a caustic residue that becomes a hazard for whoever opens the drain next.
Mismatched materials cause slower failures. Joining dissimilar metals directly can cause corrosion at the joint over time, which is why transition fittings exist.
Working on gas is the one with genuine safety consequences rather than just cost.
If you can smell gas, do not switch anything on or off. Turn off the gas at the meter if it is safe to reach, open doors and windows, leave the property, then call us or the gas emergency line. Gas work must be carried out by a licensed gas fitter, so please do not attempt a repair yourself.
The general rule is straightforward. Anything that connects to the drainage system, the water supply or a gas line is licensed work. Replacing a washer or clearing a trap is not.
For a burst pipe or a serious leak, turn the water off at the mains tap before you call. If water is anywhere near power points, the switchboard or light fittings, stay clear and treat it as an electrical hazard. Do not enter standing water in a room with live power.
