how many sewers are there in the world?

Question: how many sewers are there in the world?
- Keywords:
  sewer,
  world
Asked by 292radh29 to Olivia on 8 Mar 2017.
- Olivia Bailey answered on 8 Mar 2017:
  
  mmmm not sure – not everyone has a sewer, some people have to go on the side of the road but in the UK we have about 350,000,000 meters of sewer pipe!

Question: how many sewers are there in the world?