A block has one utility connection and one bill. Sub-meters measure each unit inside it, so the bill can be divided by consumption rather than by assumption.
The four numbers
A defensible sub-metered charge shows four numbers, every time:
- Previous reading: where the meter stood at the last bill.
- Current reading: where it stands now.
- The difference: units consumed.
- The rate applied: what one unit costs.
If a charge does not show all four, it cannot be checked, and a charge that cannot be checked will eventually be disputed by somebody who is right.
There is a fifth check that costs nothing: last month's current reading should be this month's previous reading. A gap means a reading was missed or estimated, and consumption has landed in the wrong month.
Reading discipline
Read on the same date each month, as near as the caretaker's rounds allow, and put the period covered on the bill. Where a reading genuinely cannot be taken, estimate it, but say on the bill that it is an estimate, and true it up on the next actual reading rather than letting the estimate quietly become the baseline.
Note the meter serial on every reading. In a block, the single most common billing error is a reading taken from the neighbouring unit's meter, and the serial is the only thing that catches it.
The reconciliation gap
The sum of the sub-meters rarely equals the main meter. Common areas consume, meters have tolerances, and old pipework loses water.
Somebody has to decide how that difference is handled. The options are all defensible: absorb it as a landlord cost, recover it through service charge, or apportion it across units on a stated basis. What is not defensible is quietly inflating everyone's rate to cover it, because that is the one approach that cannot be explained if anyone asks.
The rule should be in the agreement, and the gap should appear as its own line rather than hidden inside everyone's unit rate.
Rate mark-up
Charging occupiers more per unit than the supplier charges the building turns cost recovery into a margin. Whether that is permitted depends on the arrangement and the applicable rules, so take advice rather than assuming.
What is never defensible is doing it silently. A legitimate administrative cost should appear as its own named line rather than as an unexplained uplift on the tariff.
Where there are no sub-meters
Where a block has one bulk bill divided between units, ask which basis is used, whether equal shares, occupancy or unit size, and whether that basis is stated in the tenancy agreement.
Three rules apply whichever you use. State the method in the lease, not just in practice. Show the whole bulk bill on the tenant's statement alongside their share, so the split can be checked. And keep the method stable, because changing the basis mid-tenancy, even to something fairer, reads as a price rise.
A leak on a sub-meter
A leak is metered like any other consumption, which is how a tenant ends up with a bill ten times normal for water they never used.
- Verify. Read the meter with everything in the unit turned off. A meter still moving is a leak, and where it is moving tells you whether it is inside the unit or in the supply line.
- Fix immediately. Every day of investigation is metered.
- Attribute honestly. A failed cistern valve, a cracked supply pipe or a faulty fitting is a building problem and a landlord cost. A tap left running is not. Concealed leaks in the supply line are almost always the landlord's.
- Agree the adjustment on a stated basis. The usual approach is to charge the tenant their normal consumption, taken as an average of recent months, and treat the excess as a landlord cost or a shared one, on terms the lease sets out.
What goes wrong
Bills show a total and nothing else. The commonest failure, and it converts a transparent system into an opaque one.
Readings drift. Taken on the 3rd one month and the 27th the next, producing bills that swing for no reason the occupier can see.
Standing charges are hidden in the unit rate. Common-area power, the borehole pump and tanker deliveries are real shared costs and belong in a named line, usually within service charge, not folded into everyone's per-unit tariff.