Written in 1954, Larkin uses free verse, no rhyme scheme and three tercets- breaking that one structure in the final stanza.
The lack of structure makes the poem flow neatly, as if it were water running through a stream. (free flowing)

Water is a prominent thing in many cultures- holy water or baptisms in Christianity, making it a common religious symbol- it is also a basic necessity, and yet is a privilege in some places. It is simple, transparent, and pure- his view is that religion has become too complex.
His religious symbolism can be alienating, water shouldn’t be although it could end up being alienating, as many religions are and there is no reason that he shouldn’t fall prey to this as well. (Link to An Arundel Tomb, forgotten/lost intentions)
Water is also cleansing, and in a scientific status it always balances itself parallel to the surface it is on.

Perfect religion?
Uses familiar symbols of religion- lack of originality
Informal tone.
Mirrors the simplicity of water.