RUBS utility billing: how do you split one water bill among apartments?
Ratio utility billing (RUBS) takes the building's single water, sewer or trash bill and divides it among units by a formula, usually the number of occupants, the square footage, or a mix. It works only if the lease allows it, the formula is disclosed, and you charge no more than the bill. Oregon's statute shows what a careful state requires: a written agreement, a bill within 30 days, the provider's bill on request, and no markup.
What RUBS is and when owners use it
Many older apartment buildings have one water meter for the whole property. Installing a meter per unit (submetering) can be costly or impossible in old plumbing. RUBS is the alternative: the owner pays the utility's bill, then bills each unit a share based on a ratio. The money that comes back is a reimbursement of a cost, not extra rent.
States treat it very differently. Some regulate allocation formulas through their utility commission and require registration; others regulate it through the landlord-tenant statute; some say little. Before you start, look up your state's statute and, for water, your state utility commission's rules. This post uses Oregon's rule because it is short and specific.
The common formulas
| Method | How a unit's share is set | Good fit | Weak spot |
|---|---|---|---|
| By occupants | People in the unit divided by people in the building | Water and sewer, where use follows people | You need a current, honest occupant count |
| By square footage | Unit size divided by total rentable size | Trash, common heating | A single person in a large unit pays more |
| Mixed | Part by occupants, part by size | Buildings with very different unit sizes | Harder to explain on the bill |
| Flat per unit | Equal share for every unit | Small buildings with near-identical units | Ignores how many people live there |
Whatever you pick, take out first any share for common areas you should carry yourself, such as irrigation, a laundry room or an office. Write the method and the common-area deduction in the lease so every tenant sees the same formula.
A worked split
Example a made-up 8 unit building gets one water and sewer bill of $1,280 for May. The owner deducts 10% ($128) for landscape irrigation, leaving $1,152 to split by occupants. The units have 1, 2, 2, 3, 2, 2, 1 and 3 people, or 16 in all, so each person's share is $1,152 divided by 16, which is $72. The one-person units owe $72, the two-person units $144 and the three-person units $216. Two at $72, four at $144 and two at $216 add up to $1,152.
Put the provider's total, the deduction, the method and each unit's number on one page. If a tenant asks how their $144 was reached, you can answer in one line.
Oregon as a model: what ORS 90.315 requires
Oregon's statute on utility and service charges, ORS 90.315, is a clear checklist. In Oregon these are requirements; elsewhere they are a sound habit.
- A written rental agreement must provide for the charge, and common-area charges must be described separately from charges for the unit.
- The landlord bills the tenant in writing within 30 days after receiving the provider's bill, stating rent and the utility charge separately if they share a bill.
- The agreement or bill explains how the provider assesses the charge and, for a bill that covers several tenants, how it is allocated among them.
- The landlord includes a copy of the provider's bill or says the tenant may inspect it and get a copy for a reasonable copying cost.
- Payment is timely if made by a date at least 30 days after the bill is delivered.
- The charge may include only the cost billed by the provider. The one exception is an added amount of up to 10% for cable, video or internet, under conditions.
- A utility charge is not rent or a fee. Unpaid utilities are not grounds for a nonpayment-of-rent termination under ORS 90.394, though they may be cause under ORS 90.392.
If the landlord breaks these rules, the tenant may recover one month's rent or twice the amount wrongly charged, whichever is greater.
Example a made-up Oregon owner adds a $3 monthly billing fee to each of 8 units' water charges for a year. Each tenant was overcharged $36. Twice that is $72, but one month's rent is $1,350, so each tenant's claim is $1,350. Across 8 units, $288 of fees could cost $10,800.
Oregon also places utility charges third, after past-due and current rent, in the order it requires payments to be applied. Our post on payment application order covers that rule.
Recording it in your books
Keep the provider's bill as an expense in utilities (Schedule E line 17) and the tenant reimbursements as their own income account, not mixed into rent. That keeps the building's true water cost visible, makes the yearly reimbursement total easy to check against the bills, and shows a tenant or an auditor that you charged no more than you paid.
In DoorKeeping
DoorKeeping's AI reads the water bill and codes it to utilities in the property's books, and you approve it. Reimbursements tenants pay land in your own bank account, where the bank feed matches them using each tenant's memo and exact-cent amount. You can ask Claude or ChatGPT to total a year of water bills against a year of reimbursements for one property. DoorKeeping does not tell you whether RUBS is allowed in your state; check your statute and utility commission.
Sources
- Oregon Revised Statutes chapter 90, including ORS 90.315 and 90.220, read Oct 30, 2026
Questions
- Is RUBS billing legal?
- It depends on the state, and some states regulate water allocation closely through their utility commission. Where it is allowed, it generally requires a lease that provides for it and a disclosed formula. Check your state before you start.
- Can I add an admin fee to a RUBS bill?
- In Oregon, no: the charge may include only the provider's cost, except up to 10% for cable or internet under conditions. Other states differ, so check yours.
- Can I evict for unpaid water charges in Oregon?
- Not as nonpayment of rent. ORS 90.315 says a utility charge is not rent, though unpaid charges may be grounds for a termination for cause.
- What is the fairest RUBS formula?
- For water and sewer, splitting by occupants usually tracks use most closely. Whatever you choose, deduct common-area use first and disclose the method in the lease.