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RUBS is on borrowed time. How to switch your park to submeters.

By · Published February 18, 2026 · 9 min read

If you split one master water bill across your tenants by a formula, you are using RUBS, short for Ratio Utility Billing System. It divides the park's bill by head count, home size, or lot count instead of measuring what each home used. It is easy, and it is getting squeezed from two directions: states are tightening the rules, and tenants dislike paying for a neighbor's leak.

Here is what is changing, and how to move your park onto real submeters the right way.

RUBS versus submeters, in one minute

A master meter measures the whole park. The utility bills the park, and the owner either eats the cost or guesses a flat amount into rent. RUBS is one step better: you take that master bill and divide it by a formula. But a formula is not usage. The careful family in a small home can pay the same as the four-person household with a dripping toilet, because the split does not know who ran the water.

Submeters put a small meter at each lot. You read each meter, bill each home for what it used, and the fairness question goes away. The tenant who uses less pays less.

Why the ground is shifting under RUBS

Two forces are working against formula billing.

First, the no-markup rules. Almost every state that lets you pass water through to tenants says you can bill only what it cost you, with little or no add-on. RUBS runs into this because a formula can easily bill out more than the park was charged, which is exactly what the rules forbid.

Second, states are starting to restrict formula billing outright. Minnesota is the clear first mover: a 2024 law added to Minnesota Statute 504B.216 the flat line that "apportionment of electricity is prohibited," a statewide ban on splitting a master electric bill by formula for residential rentals, with tighter rules for gas and water on leases signed or renewed from January 1, 2025. Electricity is not water, and how far the Minnesota rule reaches into every park-lot tenancy is still being worked out. But the direction is not subtle. When a state decides a formula is not fair enough for the electric bill, the water bill is on the same list eventually.

No other state has a full statewide ban on formula electric billing yet. So this is not a fire drill. It is a reason to convert on your own schedule, before a deadline or a tenant complaint sets the schedule for you.

The case for submeters, beyond compliance

Even if your state never bans RUBS, submeters pay for themselves in two ways.

They cut usage. When people pay for the water they use, they use less. The largest study on this, the National Submetering and Allocation Billing Program Study sponsored by the U.S. EPA and apartment-industry groups, found submetered homes used 15.3% less water than homes where water was bundled into rent, about 21.8 gallons per unit per day. In a park on city water, that is money off the master bill every month.

They catch leaks. A submeter that suddenly reads high is a running toilet or a broken line under a home. On RUBS you would never see it, because the cost just gets spread across everyone. On submeters, one lot's spike is a repair you can make before it drains the aquifer or your wallet.

The short version: RUBS is easy but hard to keep fair and legal, and it hides leaks. Submeters cost more to install, then save water, catch leaks, and keep you clear of the no-markup rules. For most parks staying long-term, the meters win.

How to switch, step by step

Converting is not just bolting on meters. In several states there is a required process, and skipping it can void your right to bill. Here is the order.

1. Read your state's rules first. Before you buy a meter, learn three things for your state: whether you must register before billing, whether you can add any administrative fee or must bill at pure cost, and what notice and steps you owe tenants before switching. These vary a lot, and getting them in the wrong order is the common mistake.

2. Register if your state requires it. Texas is the sharp example. Owners who submeter or allocate water have to register with the Public Utility Commission before they send a single bill. Bill first, register later, and you are out of compliance from day one.

3. Follow the tenant-notice process, especially the trial period. Oregon shows how involved this can be. Under Oregon Revised Statute 90.574, before you convert billing methods you owe tenants at least one month of written notice, a tenant meeting to explain the change and hand out a sample bill, and a trial: the first three billing periods run as mock bills so residents see what they would owe before a real charge lands. Not every state asks for this, but where it exists, it is not optional.

4. Install accurate meters. Use submeters that meet the recognized accuracy standard, and record a clean starting read for every lot on the day you go live. Your first real bill is only as trustworthy as that baseline read.

5. Bill at cost, itemized. Set the tenant charge from the utility's own rate, with no profit built in. On the bill, show the prior read, the current read, the rate, and the service period, so any tenant can check the math. An itemized bill is both the fair way and the legal way, and it is your answer if a charge is ever disputed.

6. Tell tenants what is changing and why. Send a plain letter ahead of the first real bill: you are moving to metered water, here is your meter, here is how to read your bill, and your total now reflects your own use. Frame it as fairness, because it is. The light user is about to pay less.

What good looks like after the switch

A tenant's bill shows lot rent on one line and water on another: last read, this read, gallons used, the rate, and the total, at cost. A high read at lot 14 flags a leak you fix that week. Your master bill drops as usage falls. And if your state ever bans formula billing, you are already done and did it on your own timeline.

If you want the plain-English version of the fairness and no-markup basics first, see our post on how to bill tenants for water the legal way. For the numbers, our free submeter water-bill calculator shows what a tenant owes from a prior read, a current read, and your rate.

Lot Sidekick does the metered side for you: your manager keys the reads from a phone, each lot's usage is itemized at your utility's rate with no markup, and the water line drops onto the bill next to rent. You can run the same math by hand with the calculator above. The rules and the steps are the same either way.

Sources

General information, not legal advice. Utility-billing and conversion rules vary by state and change over time. Confirm your state's registration, notice, and no-markup rules with a local attorney who knows manufactured-housing law before you convert.

Lot Sidekick itemizes submetered water on every bill automatically. Your manager keys the reads from a phone and each tenant is billed at cost. Send your spreadsheet and I'll set up your park, or see the live demo, or call (425) 405-0734.