The by-law should be an exclusive use by-law whereby the 9 lots have exclusive use of the common property water meter. The by-law can then set out how the costs are distributed between the 9 owners which should be up for negotiation between the users but does not necessarily have to be in line with unit of entitlements. The by-law should also stipulate how those costs should be recovered.
The owners corporation can not raise any levies, special or otherwise, as all levies must be distributed to all owners according to the unit of entitlements registered on the strata plan.