By Andrew Keel | KeelTeam.com

It’s not the cap rate math. It’s not the LOI terms. It’s not even the environmental inspection.

The most expensive mistake I see new mobile home park investors make — and some experienced ones too — is treating water and utility due diligence as an afterthought.

I’ve seen this error destroy first-time park deals. I’ve watched sophisticated operators take on a park that looked cash-flowing at close and lose $50K–$150K+ in the first 18 months. And almost every single time, the root cause was the same: they didn’t dig deep enough into the water situation.

The Master Meter Problem

Here’s the setup: you’re looking at a 75-lot park built in 1978. Nice lot rents. Solid occupancy. Seller has been running it for 22 years. You get the broker’s OM and the water bills look fine — $2,900/month average over the trailing 12 months.

You close.

Month two, the water bill is $6,200. Month three, $5,800.

You call a plumber. He finds three slow leaks under homes — leaks that have been there for months, quietly running water into the ground. He also finds that the main line running down Lot Row C has been sweating for years, losing an estimated 3,000 gallons per day.

In six months, you’ve lost $18,000 in unexpected water costs. And you still need to spend $35,000 to repair the main line.

What happened? The seller knew about those leaks. He managed them — patching, turning off water to specific lines temporarily, doing informal repairs. His trailing 12-month bills looked clean because he’d spent the prior year actively managing the situation, not because the underlying infrastructure was healthy.

This isn’t fraud. It’s not necessarily dishonest. It’s just how older parks work — they require constant active management to keep water bills in check, and a sale is the one time a seller might pull back that active management rather than disclose it.

Why Master-Metered Parks Are a Different Animal

About 40–60% of older mobile home parks (particularly those built before 1985) operate on a single master meter: one municipal connection, one bill, one number that hides everything underneath it.

When you’re master-metered, every gallon used by every resident comes out of your pocket. A resident leaves a hose running for a week? Your bill. A toilet seal fails in Lot 23 and runs constantly for two months? Your bill. An old water line under the road corrodes and starts leaking 500 gallons a day? Your bill.

And residents have zero incentive to conserve or report leaks, because they’re not paying for water.

The Due Diligence Moves That Actually Matter

After running due diligence on 50+ parks, here’s the water protocol that protects you:

1. Get 36 months of utility bills directly from the municipality — not from the seller. Don’t accept the seller’s copies. Request directly from the municipal billing department. Sellers can doctor PDFs. Municipal records are clean. Look for seasonal spikes, trends over time (creeping bills = slow infrastructure deterioration), and any months that look unusually low.

2. Calculate gallons per lot per day — and compare to benchmarks. Take total gallons used per month, divide by occupied lots, divide by 30. A mobile home lot with one or two residents should consume 80–150 gallons per lot per day under normal conditions. If your park is running 250+ gallons per lot per day, you have a problem — leaks, irrigated common areas, or something else bleeding your water budget.

3. Do a physical walk of all main water lines. Get a plumber who specializes in utility infrastructure — not a general contractor — to walk every accessible main water line. Look for wet spots in the ground along utility corridors. Even better: run a pressure test. A properly sealed system holds pressure; a leaking one doesn’t.

4. Look under homes. Manufactured homes sit on piers or skirted foundations. Old water connections where the municipal line connects to each home are common failure points. Look for damp soil, mineral staining around connections, and soft ground near utility hookups.

5. Ask specifically about any utility bill anomalies in the last 36 months — in writing. “Have there been any months in the past 36 months where water bills were materially above or below average, and if so, what was the cause?” If a seller discloses a pipe repair that caused a spike, that’s honest. If they say no anomalies and municipal records show a $12K water bill three years ago, that’s a red flag about their credibility across the board.

For a comprehensive framework covering water, infrastructure, financials, and legal — the Mobile Home Park Due Diligence Playbook walks through exactly how we structure every acquisition review at Keel Team.

What To Do When You Already Own a Master-Metered Park

If you own a park on a master meter and you’re eating the water bill, you have three paths:

Path 1: RUBS (Ratio Utility Billing System). This allocates water costs back to residents based on a formula — typically number of occupants or lot size. It’s legal in most states, doesn’t require new hardware, and can be implemented within 60–90 days with proper lease notice periods. Most operators who implement RUBS correctly see water costs drop 25–40% within six months, because residents start conserving when they’re paying the bill.

Path 2: Sub-metering. Individual meters per lot allow you to bill residents for their actual consumption. This is the gold standard — residents only pay for what they use, you don’t subsidize anyone, and problem users get identified immediately. The downside: cost. Expect $1,000–$2,000 per lot for equipment and installation. On a 75-lot park, that’s $75K–$150K. It pencils long-term, but requires capital and planning.

Path 3: Active leak management program. If you can’t implement RUBS or sub-metering immediately, set up a systematic quarterly walk of all water connections — under homes, at meter connections, along main lines. Fix leaks within 48 hours. This won’t solve the structural problem, but it keeps bills from spiraling while you work toward a permanent solution.

The Bottom Line

Water is the most common hidden cost in mobile home park acquisitions, and it’s the most preventable. The information is available — if you know where to look and what to ask.

Every deal we underwrite at Keel Team includes a thorough utility analysis, and it’s saved us from some very costly decisions. The parks that look great on the broker’s OM but fall apart on water due diligence are actually a feature, not a bug — they’re the deals your competition will overpay for while you walk away disciplined.

Do the water work. It’s not glamorous, but it’s where deals are really made or broken.

Andrew Keel is the founder of Keel Team Real Estate Investments, owning and operating 50+ mobile home parks across the United States. Follow along at KeelTeam.com.