Surface water runoff has an impact on the water quality of the river. This is due to surface water picking up contaminants ,as it drains from the urban landscape and flows into the river.
Where does surface water pollution come from?
Your house: Incorrect plumbing could mean that waste water from dishwashers, washing machines, sinks, baths and even toilets is flushed directly into a local river. People doing their own plumbing and even professional plumbers can accidentally create these misconnections, which are a common cause of pollution to rivers and streams, especially in towns and cities.
Your driveway: When you wash your car in the driveway or on the street, the dirt, oil, and detergent laden water runs into drains and then directly into our streams, rivers, and lakes. Just as soap destroys dirt and organisms on your car, it will do the same in rivers and other bodies of water. Many of the commonly-used soaps contain phosphates, which remove oxygen from the water.
Car parks: These can be a big risk, as they are often contaminated with oil, petrol and toxic metals from cars. In heavy rain, all of this pollution would be washed off into drains, polluting nearby watercourses.
Agriculture: In more rural parts of Hillingdon, chemicals being sprayed on agricultural land, such as pesticides and herbicides, can find their way into watercourses from spray drift. This can also affect hedgerows and other habitats bordering the sprayed area. Pesticides especially can have serious effects on aquatic life. All of this pollution ends up flowing into the Crane and the Colne Rivers.
Everything that goes down the kitchen, laundry and bathroom sink or that's flushed down the toilet ends up in the sewerage system. Treated sewage is either reused or safely returned to our rivers and oceans.
Putting the wrong things down the sewer affects our ability to treat and reuse the water and can cause damage to the system. According to Thames Water, more than half of blockages are caused by fat and cooking oil. These 'fat bergs' can cause blockages resulting in flooding.