Debpaul

We are considering buying a new build property with a communal rainwater soakaway in the back garden that connects 3 other properties. A couple of questions...would appreciate any thoughts and insights 1. What is the maintenance requirements for soakaways? 2. How to get into an agreement with the neighbours for shared maintenance to avoid issues in future? Note, this is a new build and other plots are yet to be sold. 3. Would it be illegal to disallow discharge from other properties in future if maintenance of the soakaway becomes difficult.