Why this matters for the Dart: what leaves your kitchen sink either burdens the sewage works upstream of the river, or blocks the sewers so they overflow into it.
The rule: never pour fat, oil or grease down the sink, however small the amount.
The kitchen sink feels like a disposal point, but it is really the start of a long, narrow pipe to the sewage works, and it is easily defeated. British households pour enough fat down their drains every year to fill seven Olympic swimming pools, as our neighbouring charity the Westcountry Rivers Trust points out 18. Warm fat flows; cold fat sets. Combined with wet wipes in the sewer, it builds the congealed blockages known as fatbergs. There are around 300,000 sewer blockages in the UK every year 20, and when a sewer blocks, the sewage backs up and escapes wherever it can: into homes, gardens, streets, and through storm overflows into rivers like the Dart.
Cool it, scrape it, bin it. Pour cooking fat, oil and grease into an old jar, tin, yoghurt pot or foil, let it cool and harden, and put it in the bin. Save or freeze leftover gravy for another meal, or soak small amounts up with kitchen roll and bin it 19. Why it helps the Dart: fat that never enters the sewer can never help block it, and blocked sewers are a direct cause of sewage escaping to watercourses. How hard: easy, and free.
Fit a sink strainer. A simple mesh strainer in the plughole catches food scraps before they enter the drain 19. Empty it into the bin or food caddy. Why it helps the Dart: food waste feeds sewer blockages and adds to the load the sewage works has to treat. How hard: easy, costs a pound or two.
Scrape plates before washing. Scrape leftovers into the food caddy or compost rather than rinsing them down the sink. Why it helps the Dart: the same logic as the strainer, one step earlier. How hard: easy.
Choose phosphate-free and gentler cleaning products. Phosphorus is a nutrient, and rivers can have far too much of a good thing. When excess phosphorus reaches a river it can drive excessive growth of algae and water plants, which chokes the channel and starves the water of oxygen at night, harming fish and insect life 22. This over-enrichment is called eutrophication. Phosphorus is the most common reason English rivers fail their water quality standards: in the Environment Agency's assessment, 55% of river water bodies were at less than good status for phosphorus 22, and government analysis confirms that excess phosphorus is a significant factor in rivers failing to meet good ecological status 24. The law has already removed most phosphates from consumer laundry detergent (from mid 2013) and dishwasher detergent (from the start of 2017) 23, but other cleaning products vary, so look for "phosphate-free" on the label and use the dose the packet recommends rather than a generous glug. If you are on a septic tank, this matters double: harsh bleaches and antibacterial products kill the bacteria your tank relies on to treat sewage at all 25. Why it helps the Dart: less phosphorus and fewer harsh chemicals into the foul sewer means less reaching the river in treated effluent and overflow spills. How hard: easy, a swap next time you shop.
Keep the really nasty stuff out entirely. Paint, white spirit, motor oil and other chemicals should never go down any sink or drain 25 26. Medicines & chemicals explains where they should go instead.
One last kitchen thought: the dishwasher and washing machine live here too, and running them with full loads saves water as well as energy. Your water use explains why that helps the river.