Do You Charge Tenants What You Actually Pay for Water & Electricity?
Published July 27, 2026 · 7 min read
Most owners walk the rooms on the 30th or 31st to keep a clean billing cycle — but the utility company never reads its own meter on that same day. So how do you know whether what you bill tenants matches what you actually pay the state? The date mismatch isn't the problem — here's the check that actually works.
TL;DR
- •A date mismatch with the utility company's own meter reading isn't a problem — meters are cumulative, so the units even out over time
- •The accurate check is to record the MAIN meter (the whole property's or building's meter) the same day you walk the rooms, then compare UNITS — not monthly Baht totals
- •The gap between the main meter and the sum of room meters = common-area usage + loss — cost the owner quietly absorbs
- •To check whether you charge a fair rate, compare the real average rate (bill amount ÷ bill units) against what you charge tenants — not the total Baht figure
- •Charging above your real cost breaches Thailand's 2018 CPB Notice, which bans profiting from utility resale (applies to rentals with 5+ units)
Why the date mismatch isn't actually a problem
A meter is a cumulative counter — it never resets monthly. If the utility company reads on the 18th and you read on the 30th, the mid-month units simply shift into a different billing period. Over a full year it always evens out, because every unit that passes through the meter gets counted — just split across a different pair of bills. Stop trying to make the monthly Baht totals match exactly; they never will, and they don't need to.
Record the main meter alongside the room meters — the accurate method
The number worth comparing isn't the date on the utility company's bill — it's the main meter (the whole property's or building's meter) that the utility company actually bills you against.
Read the main meter the same day you walk the rooms
On the 30th or 31st, when you're already recording room meters, record the property's (or each building's) main meter at the same time.
Compare UNITS, not Baht
The main meter's usage (this month minus last month) is the property's actual total consumption. Compare it against the sum of units billed across all metered rooms.
The gap = common-area load + loss
Hallway lights, water pumps, leakage, and flat-rate/included rooms (which use real utilities but aren't counted) all show up in this gap.
Worked example (20-room dorm, June)
Those 250 units are cost the owner absorbs — without checking, you'd never know how much real cost quietly disappears every month.
Check whether you charge a fair rate — compare the real average rate
Don't compare against the posted tariff (e.g. ฿4/unit) — the actual bill includes the Ft adjustment, service charge, and 7% VAT. The simple way to find the real rate per unit is: bill amount ÷ units on that bill.
Example: a ฿9,585 bill ÷ 2,250 units = ฿4.26/unit (everything included). If you charge tenants ฿7/unit, you're charging ฿2.74/unit above your real cost — which breaches the 2018 CPB Notice banning profit on utility resale (it applies to rentals with 5+ units).
Water follows the same logic — the water authority reads the property's main meter; the gap against room meters is common-area water (floor cleaning, overflow tanks, watering plants) plus leakage.
Check this gap automatically every month — Pro members only
Recording the main meter alongside room meters works by hand using the method above, but you have to compute it yourself every month. IslandDorm members on Pro and above have a tool built into the Meters page that computes actual property usage, billed usage, and the gap automatically the moment you type the readings — no manual math.
FAQ
Do I need to record the main meter every month, or is checking occasionally enough?
Monthly is the most accurate, but checking quarterly still shows the trend — what matters is always reading it the same day as the room meters, so the units compare fairly.
What if there's no separate main meter (just one shared meter for all rooms)?
Most dorms already have a utility-company main meter installed before it splits into individual rooms — that's the meter the bill is actually calculated against. Record that one; if you can't locate it, ask the electrician who wired the building.
How big a gap counts as normal?
There's no fixed number — it depends on the dorm's size and common areas. But if the gap keeps growing month over month with no obvious reason (no new vacancy, no construction), check for a leak or unauthorized utility use.
If I've been overcharging tenants for a while, do I owe them a refund?
The law doesn't require a retroactive refund, but you should adjust the rate to match real cost starting next month. If you're worried about the lost income, see the "How to Calculate New Rent" article below — raise rent instead of profiting from utilities.
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