Many people won’t give a second thought about where the water goes when it’s flushed down the drains. It’s simply not something we ever learn about or get taught explicitly, but it can be interesting to learn where it goes, how it makes it back into rivers and how you can help the process too.

 

There are many stages involved in getting wastewater back into a usable, clean state, and you might be surprised at just how much effort is involved in transforming what you put down your drains.

FLUSHED AWAY

At the very beginning of the process, the water which you put down your drains and flushed down your toilet is led out of the property into a much larger sewer pipe under your road. All of these pipes are networked together, but some require additional pumping to get the waste moving away.

SCREENING & FILTERING

Clearly your waste water cannot simply be led back to open water sources as it is, it requires filtering, which is why there are screening plants in place. This helps to remove all sorts of things from your waste water – including the things which people shouldn’t be putting down their drain, such as face wipes and nappies. Once all of these things are removed, the grit present in the water is also removed using dedicated equipment.

PRIMARY TREATMENT

Although a lot of the solids will have been removed from the water there will still be some human waste present, and that’s what the next stage is aimed at dealing with. Put into settlement tanks, the water is left to settle, allowing the solid particles to drift to the bottom where it collects into a sludge. This material is pumped away while the  rest of the water passes over the top of the settlement tank.

SECONDARY TREATMENT

While the majority of the large particles have been taken out in previous phases, the secondary stage is aimed at removing the bugs and smaller particles which might not be visible to the naked eye.

At this stage the water is pumped with air to break down bugs, making good bacteria eat the bad, cleaning the water until all the bad bugs are gone.

FINAL STAGE

Before the water can be put back into rivers it has to go through one final stage, this is yet another settlement tank phase. This time the good bacteria are left to settle, leaving behind clear water. If this does not clean the water to the right level then additional phases can be added, such as putting the water through sand, to filter it further.