1. Was your house or property built after the 1920s?
In Britain sewerage systems have developed since Victorian times when towns and cities grew with industrialisation. The first drains or sewers were built simply to get foul drainage and wastewater away from where people lived because it was realised diseases like cholera and typhoid were spread by poor sanitation. Most of the older parts of towns and cities therefore have combined sewerage systems which take both rainfall and wastewater to the sewage treatment works.
As our towns and cities grew it was not practical to drain larger and larger areas with just one combined sewer. The amount of water, both clean rain water and foul sewage, could simply not be accommodated. So we have built separate sewers since about the 1950s and even earlier in some areas. There are two types of drains with separate sewer systems. One is for wastewater from toilets, sinks, washing machines, industrial wastes, etc and goes to the sewage works for treatment before being discharged back into rivers. The other drain is for clean surface water from roofs, roads and yards and discharges straight into the nearest river or stream. About half of all properties in Britain have separate systems.
Unfortunately, over time, the clean sewers in many areas have become polluted by misconnected wastewater. With more development, ‘urban creep’ and the trend for house alterations and DIY improvements over the last twenty years these misconnections have become more common. Pollution comes from surface water sewers because run-off from our urban areas is not always clean. Atmospheric fallout from traffic, spillages and road accidents, illegal discharges, vehicle washing and foul sewer failures all end up discharging to our rivers and beaches.
As well as wastewater getting into clean surface water drains there is a problem caused by ‘clean’ misconnections. These occur when roof drains and clean surface areas are connected to foul sewers. This excessive rainfall causes foul sewers to overflow often into rivers but sometimes even into properties. It also means that more diluted wastewater has to pumped to sewage works and then treated. This adds to treatment costs and energy use.
New properties built in the last 5-10 years may still have been built with separate drainage even if they are in a combined sewer area. This is so that if a new separate sewerage is built one day the new property can be ready to connect to it. In some areas properties might also have roof downpipes draining into soakaways in the ground. It is important that wastewater is not drained to soakaways. Your local authority or water company may know what type of sewerage system your property has.