How near for CL facilities

Tirril

I was passing a CL in Northumberland which is open all year  and which I am hoping to use in April. There was no sign of any water supply or loo emptying point (the site is open to a quiet single track public road so no tresspass involved!)  The farm was
some distance away so if you needed to go there for water you would need to take your Aqua roll in your car. Is there a policy on how far away the essential facilities can be from the site.