Drain unblockers How we test drain unblockers
Which? drain unblocker tests
We pit each drain unblocker against our purpose-built blockages to see if they can clear the obstructions they claim to shift – whether it's a kitchen blockage, bathroom blockage, or both. Only the very best will be rated a Best Buy drain unblocker.
For a waterproof kitchen blockage we combine rice with coffee, vegetable fat and animal fat. We then add 50ml of standing water before attempting to unblock the pipe in accordance with the unblocker manufacturer's instructions.
For bathrooms, we take a bundle of hair and cotton, and combine it with a liquid concoction of hard water mixed with soap and toothpaste.
We also test chemical drain unblockers on different surface materials including stainless steel, PVC and copper to see if the chemicals may damage your sink, pipes or fittings.
Some chemical drain unblockers cause an exothermic reaction (they generate heat), which can help to clear kitchen blockages, melting the fat that usually constitutes a large part of a kitchen blockage. However, too much heat may damage certain types of pipes, so we also measure the temperature change of chemical drain unblockers that cause this kind of reaction.