Joint rainwater drainage for neighbours

Questioner

My neighbors and we have a shared rainwater drain, which unfortunately goes to the main sewer via our crawl space. The drainpipe is exactly on the property line and is capped off on the neighbours' side under the ground because it goes to our crawl space via a T-piece. This rainwater drain is for both sloping roofs as well as our shared large flat roofs (living rooms are standardly extended compared to the upper floor) and also for the flat roof of our garage. This situation has been the case since the owner-occupied homes were completed 25 years ago. The neighbours now want to connect the rainwater, which comes into their completely paved garden, via a gutter to the part of the drainpipe that is capped on their side, so that all excess rainwater is drained via our crawl space to the main sewer. We do not want to allow this because this drain has already broken down during normal use, and we are afraid that sand and/or leaves will end up in this drain pipe, causing all the associated problems. The question is, can we refuse this legally? Should we/should we not allow changes to be made to this joint rainwater drainage? Thank you very much in advance for your answer. Yours sincerely,

Lawyer

You probably don't need to allow that. The existing situation concerns an easement for the drainage of rainwater that ends up on their roofs via your connection to the sewer. If the easement is recorded in writing (in which case it is stated in the title deed), then the text of this easement is decisive. If nothing has been recorded about it, then the easement as it currently exists has arisen by prescription and cannot simply be extended by the neighbours.