You ran the numbers. You underwrote the deal conservatively — or so you thought. You got a general inspection. The cap rate looked right. You closed.

Then the water main broke. Then another section. Then you called a plumber who looked at your pipes and said the words you didn’t want to hear: “These are Orangeburg pipes. The whole system needs to go.”

Welcome to the most common and most expensive mistake in mobile home park investing: underwriting aging infrastructure as if it doesn’t exist.

We’ve seen it happen to experienced operators. We’ve almost made this mistake ourselves. And we’ve spent years building a due diligence system specifically designed to prevent it. This is what we know.

What’s Actually Underground in Most Older Parks

The majority of operating mobile home parks in the United States were developed between the 1950s and 1980s. That means the water and sewer infrastructure serving those parks is 40 to 70 years old — built with materials that were standard at the time but have a finite lifespan:

Galvanized steel water lines were standard through the 1960s. Galvanized steel corrodes from the inside out, progressively reducing water pressure, leaching rust into the supply, and eventually failing with leaks and breaks. Average useful life: 40–50 years. Most of them are already past it.

Orangeburg sewer pipe — made from wood pulp and pitch — was manufactured from the 1940s through the 1970s. It was cheap, it worked initially, and it has a 50-year design life that is now up. When Orangeburg fails, it collapses. The pipe doesn’t crack — it turns to mush. Camera inspections of Orangeburg lines look like someone crumpled a paper tube. Full replacement is the only option.

Cast iron lasts longer but is vulnerable to root intrusion at joints, especially in areas with large mature trees. Once roots are in, they grow until the joint is destroyed.

The cost of replacing these systems is not small. Full water and sewer line replacement typically runs $1,000 to $3,000 per lot, depending on soil conditions, line depth, and site layout. For a 100-lot park, that’s $100,000 to $300,000. For a 200-lot park, potentially $600,000. This is not a CapEx line item that fits neatly into a value-add business plan. For a full picture of how infrastructure costs affect mobile home park valuation, see our step-by-step mobile home park valuation guide.

The Due Diligence Gap

Here’s the uncomfortable truth: most mobile home park due diligence is woefully inadequate for infrastructure.

In commercial real estate — multifamily, office, retail — there is a standard product called a Property Condition Assessment (PCA). It’s a formal, standardized engineering report covering all major building systems, prepared by qualified inspectors, accepted by lenders, and typically required as a condition of financing. It gives you cost-to-cure estimates for every deficiency.

Nothing equivalent exists for mobile home parks.

Most buyers hire a general home inspector who walks the lots, looks at roofs, tests a few water faucets, and calls it done. They’re not running camera inspections through the sewer main. They’re not pressure-testing the water distribution system. They’re not reviewing 24 months of utility bills for leak indicators — and a spiking water bill is one of the clearest signs of a distribution system problem.

The seller isn’t going to tell you the pipes are shot. In many cases, the seller doesn’t even know — or has been running the park so long that “it’s always been like that” is their honest answer. Understanding the full pros and cons of mobile home park investing — including infrastructure risk — is essential before you commit capital to any deal.

Three Red Flags to Look for Before You Write a Check

1. Utility Bills That Don’t Track Occupancy

Pull 24 months of water and sewer bills and compare them to occupancy rates. If water usage is high relative to occupied lots, you may have a distribution system leaking into the ground. This is the cheapest and most revealing infrastructure screening tool available — and almost nobody does it.

2. Repair History That’s Vague or Absent

Ask for documentation of all utility repairs in the last five years. A well-maintained park has records — invoices, work orders, photos. A park with deferred maintenance has nothing. Silence is a red flag.

3. Trees Near the Sewer Lines

Mature trees with aggressive root systems near sewer laterals are a predictable problem. Look at the site map, look at the tree canopy, and assume root intrusion exists until a camera inspection proves otherwise.

What We Do Differently

At Keel Team, every acquisition in due diligence goes through a non-negotiable infrastructure protocol:

• Sewer camera inspection of the main line and all accessible laterals. Cost: $2,000–$5,000. It eliminates surprises entirely. If the camera shows Orangeburg or severe root intrusion, we either reprice the deal or walk.
• Water system pressure test. Identifies leaks and weak points in the distribution system before they become emergency repairs after closing.
• 24-month utility bill review. We benchmark water cost per occupied lot and flag anything more than 20% above market rates.
• Infrastructure-adjusted CapEx reserves. For parks with water and sewer systems built before 1985, we reserve $800 to $1,500 per lot per year for infrastructure — carried as a hard cost in our underwriting, not an optimistic footnote.
• Trenchless repair assessment. Where full replacement isn’t economically feasible, we get quotes for pipe lining — a trenchless technique that can extend line life by 25–50 years at 40–60% of full replacement cost.

This protocol is fully documented in our Mobile Home Park Due Diligence Playbook — a resource that walks through our complete acquisition checklist, including the infrastructure questions most buyers skip. If you’re also evaluating how to structure your acquisition financing around deals with infrastructure needs, see our guide on creative financing strategies for mobile home park acquisitions.

The New Regulatory Wild Card

If aging infrastructure weren’t enough, new federal and state environmental regulations are adding another compliance layer.

The EPA’s PFAS standards require testing and remediation in communities where contamination is detected — and many older parks with private wells or on-site water treatment have never been tested. EPA fines for septic contamination run up to $10,000 per day. Florida, California, and several other states are adding nutrient discharge limits for on-site wastewater treatment systems.

If your park has private water or on-site sewer — common in rural communities — you need an environmental compliance review as part of your due diligence. Full stop. The liability exposure is not abstract.

How to Underwrite It Correctly

Stop treating infrastructure as a binary: either there’s a visible problem or there isn’t. Infrastructure always degrades. The question is where it is on that curve and how fast it’s moving.

Model infrastructure reserve as a hard cost:

• Pre-1980 water/sewer: $800–$1,500 per lot per year
• 1980–1990: $400–$800 per lot per year
• 1990–2000: $200–$400 per lot per year
• Post-2000, documented maintenance: $150–$300 per lot per year
• Roads and pavement: $15–$25 per linear foot for repaving, budgeted on a 15-year replacement cycle

At $800 per lot per year for a 100-lot park, that’s $80,000 annually in reserves. That changes your NOI. That changes your cap rate math. That changes whether the deal makes sense.

Better to know that before you close than after the third main break in fourteen months.

The Bottom Line

Infrastructure is the most underpriced risk in manufactured housing investing, and it’s getting more expensive every year as the cohort of aging parks keeps aging. The operators who get hurt are the ones who close on deals without looking underground.

Sewer cameras are cheap. Voided business plans are not.

Do the inspection. Model the reserves. Ask the hard questions before you wire the money — not after.

Reach out at keelteam.com if you want to walk through our infrastructure due diligence process for an acquisition you’re evaluating.

Frequently Asked Questions

What is Orangeburg pipe and why is it a problem in mobile home parks?

Orangeburg pipe is a type of sewer pipe made from wood pulp and pitch that was commonly used from the 1940s through the 1970s. It has a design life of roughly 50 years — which means most Orangeburg in operating mobile home parks is already past its useful life. When it fails, it doesn’t crack; it collapses entirely. There’s no partial repair. Full sewer line replacement is the only fix, which can cost $1,000–$3,000 per lot. A sewer camera inspection during due diligence is the only reliable way to identify it before you close.

How much should I budget for infrastructure reserves in an older mobile home park?

For parks with water and sewer systems built before 1980, budget $800–$1,500 per lot per year as an infrastructure reserve. Parks built between 1980–1990 warrant $400–$800 per lot. These are hard costs that should reduce your underwritten NOI — not optimistic footnotes. Carrying inadequate reserves is one of the most common reasons value-add mobile home park deals run into financial trouble in years two and three.

What does a mobile home park infrastructure due diligence inspection cost?

A sewer camera inspection of the main line and accessible laterals typically costs $2,000–$5,000, depending on the size of the park and the number of lines. A water system pressure test adds another $500–$1,500. These are among the highest-ROI due diligence expenses available — a $5,000 sewer camera that reveals $200,000 in deferred infrastructure costs is one of the best investments you can make before closing.

What are the signs of failing water infrastructure in a mobile home park?

The clearest early signal is water usage that runs high relative to the number of occupied lots. Pull 24 months of utility bills and benchmark water cost per occupied lot against market averages. Usage more than 20% above expected rates often indicates distribution system leaks. Other warning signs include inconsistent water pressure across the park, rust-colored water, and a history of recurring main breaks. Galvanized steel lines — common in parks built before 1970 — are the most frequent culprit.

Do PFAS regulations affect mobile home parks?

Yes, particularly parks with private wells or on-site water treatment systems. The EPA’s PFAS standards require testing and, where contamination is found, remediation. Many older parks that rely on private water have never been tested. If a contaminated well is discovered after closing, the liability exposure — including potential fines and remediation costs — falls to the new owner. Environmental compliance review should be a non-negotiable part of due diligence for any park with private water or on-site wastewater treatment.

Keel Team acquires and operates mobile home parks in the Southeast and Midwest, focused on stable communities with strong regional demand fundamentals.