Key points
- A sewer smell usually comes from a P-trap whose water has evaporated in an unused drain; run water in it at least once a month.
- A cup or two of water in a rarely used drain restores the seal, and a layer of mineral oil on top slows evaporation.
- Banging pipes (water hammer) come from quick-closing valves; the International Plumbing Code requires an arrestor where quick-closing valves are used.
- Water hammer arrestors must conform to ASSE 1010.
Most everyday plumbing problems have simple causes; what matters is knowing what you can fix yourself and what needs a plumber.
1) Sewer smells
Every basin, floor drain and shower has a "P-trap": a curved section of pipe that holds a little water, and that water is the barrier keeping sewer gases out of the house. When a drain isn't used for a while, the water slowly evaporates and the smell gets in1.
The fix1:
- Run water in all basins, showers and floor drains at least once a month.
- Pour a cup or two of water into rarely used drains to refill the trap.
- For drains that are almost never used: once there is water in the trap, pour in a little mineral oil; it forms a layer on the water that greatly slows evaporation.
2) Banging pipes (water hammer)
The loud "bang" when a tap closes or the washing machine stops is caused by suddenly stopping the flow of water, which sends a pressure wave through the pipes. The International Plumbing Code (IPC), section 604.9, requires flow velocity to be controlled to reduce the possibility of water hammer, and a water-hammer arrestor wherever quick-closing valves are used, conforming to ASSE 10102.
Examples of quick-closing valves: solenoid valves in washing machines and dishwashers, and single-lever mixers closed quickly. Ignoring repeated banging may stress joints over time (practical note).
3) Low water pressure
Common causes and practical fixes.
- At one tap: usually a blocked aerator; unscrew and clean it.
- Hot water only: scale in the water heater or a half-closed valve.
- Whole house: weak or faulty pump, low roof tank, main valve not fully open, or a large leak. See leak detection.
4) Blockages
- Don't pour oil and fat down the kitchen sink; it solidifies in the pipes.
- Use hair strainers in the shower and basin.
- Strong chemical drain cleaners are dangerous; never mix them with bleach or anything else. See safety.
- Repeated blockages in several fixtures at once point to the main line or its slope: call a plumber.
5) Hot water
Water heater problems (leaks, noises, no hot water) are also safety issues; the safety valve and electrical connection are not for amateurs. See water heater safety.
6) When to call a plumber immediately
- A continuous leak you can't stop: close the main valve first.
- Water near sockets or the consumer unit: switch off the power and don't touch the water.
- Sewage backing up through floor drains.
- A water heater constantly discharging from its safety valve.
Sources
The number next to a statement points to its source in this list. Sources back the general information; anything marked “practical advice” is editorial experience, not a quoted source. Anything that affects safety, structural design or electrical installations needs a licensed professional, and in Saudi Arabia the binding reference is the Saudi Building Code.
- 1What's That Smell? Understanding Sewer Odors and P-Traps — South Davis Sewer District
- 2International Plumbing Code — Section 604.9 Water Hammer (ASSE 1010 arrestors) — International Code Council