I have four 200lt tanks in and around my house and they are always overflowing soon after a fair rain.
In the winter nearly always full
I am just in the process of purchasing two 1000lt ibc tanks to catch it all!
Keeping it clean is the key use filter/sieve to stop muck going into tank!
around the 17 May my tanks were empty...Summer I thought Huh...
now overflowing again!
but no problems thats what the ro's for !
Just a tip use your ro at least once a week just to stop damage to filters!
All I do with rainwater is pump it through a mesh filter, a spun debris filter (£1 Wintex)
and then the Di resin into holding tank

000tds