Question Author
Having your drains blocked is a total nightmare, nothing worse. However, we had a really nice young man turned up first thing this morning, and cleared it within about half an hour.
We had a chat with him as to how wipes get into our drain, and general other things drain related. One thing he did say, is the toilet paper you can get these days is very thick and although it does break down, it requires quite a lot of flushing. Because people are on water meters, and also being conscious of wasting water, possibly enough flushing doesn't go on to properly get rid of it. As it turns out, we waste a great deal of water trying to get the hot tap to run (combi boiler), so he suggested to catch the water wasted in a bucket, and use that as an extra flush. Also, he said, if you shower rather than bath, now and again to fill a bath and let that go down. The large rush of water helps to move little clogs along.
Regarding the wipes, he said that in very heavy downpours, the sewers sometimes can't cope with the sudden onslaught of water, and it can backflow, bringing with it things that you may not put down there, but other people do, i.e. wipes. As our drain is the last one if water is backflowing, there is nowhere for it to go but down our drain. This is one of the reasons the water companies say is why they outflow sewage into rivers and the sea, rather than it coming back up the drainage system. Neither should happen if the sewage system is properly upgraded. But then, wet wipes shouldn't ever be put into the toilet, and the manufacturers should make it clear on the packaging that none of these wipes are flushable. So - rant over and on we go.
He suggested contacting the water company as he believed there is some kind of valve you can get to stop this happening. If the shared drain gets blocked it is their responsiblity to sort out. He did say also that it is good practice to hose your drains out annually to ensure any little clogs don't build up into blockages.
So my question was answered, and now we will contact the water company.