Should a plastic water tank be reinforced to stop it flexing when the
ballcock goes up and down?

I've been replacing the rusty metal tanks with plastic ones,
and thinking that every time the ballcock goes up and down
it flexes the plastic, which could break after a few years.

The one I put in a few days ago overflowed last night.

I could move the holes lower.
any advice please?

[g]

http://www.wiki.diyfaq.org.uk/index....mbing_Articles
doesnt help with cold water plumbing