Re: Backyard temporary swimming pool
I'm not aware of any regulations.
You probably need, definitely want, the OK of the landlord, particularly if the pool is up longer than a day or two (I think the grass underneath may be damaged somewhat if it's up for weeks).
Not sure, but you'll probably also need the consent of your co-tenants as it affects the way they can use the common ground. This is particularly important if children are around: while a pool is a nice thing it's also a bit of a hazard. Plus, in such a case you should expect for the parents to only say OK if the children are allowed in, too.