Gareth J. Bywater is the son of Harold Bywater and Eunice Mary Price.

Gareth was born in 1940 in Birmingham, Warwickshire.

Gareth married Gillian Plant in 1963 in Birmingham, Warwickshire.

He had the following children from his marriage to Gillian Plant:

- Steven J. Bywater	born in 1965 at Birmingham, Warwickshire.
- Sarah Jane Bywater	born in 1967 at Birmingham, Warwickshire.
- Richard Oliver J. Bywater	born in 1979 at Birmingham, Warwickshire.

Details of Gareth's occupation are not known.