RUBS billing: what it is and when it's the right tool
RUBS — a Ratio Utility Billing System — is how a property bills utilities back to residents when there’s one master meter and no individual meters. Instead of measuring each unit’s usage, the property’s actual utility bill is divided among residents by a formula: a ratio. It’s common in apartments and mobile home parks, it’s cheaper to start than installing meters, and it’s also the utility practice most likely to be regulated, disputed, or both. This page explains how it works, how the ratios are typically built, and how to decide between RUBS and submetering — in plain language, with the honest caveats.
How RUBS works
The mechanics are simple. The property receives one bill from the utility — say a month of water for the whole park or building. Management then allocates that bill across units using a written formula, and each resident’s statement shows their share. The utility gets paid once; the allocation happens on the property’s books.
Everything that matters about RUBS lives in one question: is the formula fair, consistent, and written down? A defensible RUBS program uses the same methodology every month, can show any resident how their number was produced, and allocates only what the property was actually billed.
How the ratios are typically computed
There’s no single standard formula; these are the allocation bases you’ll commonly see in practice, alone or blended:
- Occupancy. Each unit’s share scales with the number of people living in it — the closest proxy for water use. Requires keeping occupant counts current.
- Square footage. Shares scale with unit size. A better fit for utilities that track space (heating) than for water.
- Equal split per unit/lot. The simplest version: every unit pays the same share. Easy to explain, roughest as a proxy for actual use.
- Blends. Some formulas weight a base share per unit plus an occupancy factor, trying to balance simplicity and fairness.
Two practices separate clean RUBS from trouble, whatever the base: deduct any common-area usage before allocating (residents shouldn’t pay for the clubhouse irrigation as if it were theirs), and keep the formula consistent — changing the math month to month is how billing disputes start.
Where it’s regulated
This is where we have to be careful, and where you should be too: RUBS rules vary by state, by utility type, and sometimes by property type — there is no national rule. Some jurisdictions allow it with disclosure requirements, some restrict what can be passed through, and the rules change. We’re not going to recite a state-by-state list from memory, because a wrong regulatory claim is worse than none. Check your own state’s law, or ask a landlord-tenant attorney, before building a RUBS program.
The one place we can point to chapter and verse is the market we serve: Colorado mobile home parks. Water billing in parks is governed by C.R.S. § 38-12-212.4, which caps charges at the actual cost billed to the park, requires a methodology that is “reasonable, equitable, and consistent,” requires annual disclosure of the methodology and rate schedule, and dictates what each monthly bill must show. Our Colorado utility billing guide walks through that statute requirement by requirement — if you run a Colorado park, start there.
RUBS vs. submetering
Submetering is the other path: a real meter on each unit or lot, so residents pay for what they actually used. The honest comparison:
- Precision. Submetering wins outright — actual usage ends most fairness arguments. RUBS is always an approximation, and residents know it.
- Upfront cost. RUBS wins — it’s a formula, not hardware. Metering every lot has a real installation cost, plus meters to read and maintain.
- Conservation. Submetering gives residents a direct reason to fix the running toilet; under RUBS, one household’s leak is everyone’s bill.
- Regulatory posture. Rules for both vary by state, but formula-based billing tends to draw more scrutiny than actual-usage billing. Whichever you use, the requirements where you operate — disclosure, caps, statement contents — are the starting point, not an afterthought.
A reasonable rule of thumb: RUBS is the pragmatic tool when metering is impractical or the property is small, and submetering is worth pricing out as the property grows or disputes recur. Either way, the billing math has to be done the same defensible way every month.
Where we fit
That defensibility is the product. CollectLotRent does utility pass-through for small mobile home parks — one written methodology applied identically every month, actual-cost allocation, and statements with the lines Colorado requires. If your park’s RUBS math currently lives in a spreadsheet and your confidence in it lives on hope, tell us about your park below.