That makes the situation somewhat debatable and, given the age, subject to common usage over time (think of it like a 'tradition'). However, at the outset the general thinking is that the person(s) benefiting from the easement are the ones who have to maintain the pipes - with the provision that reasonable access to do so is inferred. The person whose land the pipes pass generally only has an obligation not to obstruct the use and reasonable access. Outside that, it's the other persons' responsibility.