When the Math Doesn’t Move: Water Pressure, Affordable Housing, and the Infrastructure Gap Nobody Wants to Pay For

What happened on this site?

A Texas developer planned 190 affordable housing units and could not make the water work. This one has stuck with me. After a look at the site's water system, the plan dropped to 109 units, a 43 percent cut, to bring pressure up.

It was not enough. The hydraulic model of the 109-unit plan showed 31 psi at street level during peak demand. A three-story building gives up about 12 psi to elevation before water reaches the top floor. That left about 19 psi at the third-floor fixtures during a fire.

Twenty psi is the number every Texas water engineer carries around. This site was one psi under it.

Why can't you just cut units until the pressure works?

Because unit count is not what costs the pressure. Building height is. Water loses about 0.433 psi for every foot it climbs, which is roughly 4 psi per story. Fewer units lowers demand a little. It does nothing about the climb to the third floor.

To fix the pressure by cutting alone, you would have to cut height. Cutting height kills the unit count that makes the project pencil in the first place.

So you end up with three constraints on one site, and none of them move:

• You cannot raise rents. It is affordable housing, so the revenue ceiling is fixed.
• You cannot skip fire protection.
• You cannot argue with elevation.

When those three meet, the math either works or it doesn't. Here it didn't.

What does the Texas 20 psi rule actually require?

It is a design rule for the public water system, not for the building. 30 TAC §290.44(d) requires a system to hold 35 psi at all points in its distribution network at 1.5 gallons per minute per connection. Where the system provides firefighting, it must also hold 20 psi under combined fire and drinking water flow.

What reaches a third-floor fixture or sprinkler head is a plumbing and fire sprinkler design question that sits on top of what the main delivers.

That distinction does not rescue this site. The utility has to hold its own minimums across its whole system. A three-story building at the edge of a weak pressure area leaves the building with no margin and the utility with a problem area it has to manage for decades.

Why didn't booster pumps, a pump station or a tank fix it?

Each one solves part of the problem, and none of them pencil for affordable housing on this site.

• Booster pumps in the building raise domestic pressure at the fixtures, but a domestic booster does not supply the sprinklers. They are also an operating cost the owner carries for the life of the building.
• A pump station fixes more of the pressure problem, but it puts the area on pumps the utility must keep running. TCEQ's same §290.44(d) expects those pumps to draw from a storage tank unless the design engineer gets an exception. Texas Water Code §13.1394 also requires a utility to hold 20 psi, or a pressure TCEQ approves, through a power outage longer than 24 hours, under an approved emergency preparedness plan. Backup generators are one way to do it.
• An elevated storage tank solves everything. It is also the most expensive of the three, and an affordable project cannot recover it through rent.

Why did the utility say no when it wanted the project?

Because low-pressure developments are a headache that never ends. The town's water superintendent had been working this site for four years. He wanted it built. His answer was still no.

His reasoning was direct. Low-pressure developments are a continuous operational headache, and the utility did not want another problem area on its water system. I cannot argue with that. Multiple developers tried this site. Every one of them walked away.

Who pays for the infrastructure when affordable housing can't?

Right now, nobody. Smaller Texas towns often have systems that were never built to push water to the top of three-story buildings. Fixing that takes upstream investment, a pump station, a tank or bigger mains.

A market-rate project can sometimes carry that cost in its pro forma. An affordable project, with fixed rents and thin margins, has no way to recover it. So nothing gets built.

What should Texas developers take from this?

Water pressure is a threshold question, not a detail to confirm after you buy the land. For any multi-story project, run the hydraulics during site feasibility and due diligence.

Know three numbers before you commit: the pressure at the street during peak demand, the loss to your top floor, and the gap between the two and what the utility and the fire sprinkler design need. On this site, four years and several developers got to the answer a model could have shown at the start.

What would you do with this site?

Limits: the site details here are anonymized and come from my own account of the project. The rules cited are the Texas rules as they read in October 2026, and the right fix for any site depends on its own utility and building design.

Frequently asked questions

What is the minimum water pressure in Texas?

TCEQ requires public water systems to be designed for 35 psi at all points in the distribution network at 1.5 gallons per minute per connection, and 20 psi under combined fire and drinking water flow where the system provides firefighting.

How much water pressure does building height cost?

About 0.433 psi per foot of rise, or roughly 4 psi per story. A three-story building loses about 12 psi before water reaches the top-floor fixtures, no matter how many units it has.

Why can't booster pumps solve the pressure problem for affordable housing?

A domestic booster raises fixture pressure but does not supply the sprinkler system. It also adds an operating cost for the life of the building that fixed rents cannot absorb.

I'm a developer looking at a three-story affordable project in a small Texas town, and the city says pressure is tight. What should I ask before I go under contract?

Ask the utility for the modeled pressure at your connection during peak demand and during fire flow. Then have an engineer take off the elevation loss to your top floor and check it against the plumbing and sprinkler design. If the gap needs a pump station or a tank, find out who would own it and pay for it.

I'm a city water superintendent and a developer wants to build three stories at the edge of our low-pressure area. What should I look for in their submittal?

Look for a hydraulic model that shows your system still meets the 35 psi and 20 psi design minimums with the new load, and a clear plan for who builds and operates any pump station or storage it needs.

Related resources

• How to Conduct a Fire Flow Analysis for a Texas Development or Subdivision
• Hydraulic Modeling for Dallas High Rise Developments: Why Pressure Zone Design Matters More Than You Think
• What a Utility Feasibility Study Actually Tells You, and When to Get One
• How to Read a Hydraulic Grade Line

Evaluating a Texas site where water pressure might not work?

We run the hydraulics during due diligence, so you know whether the site can support the building before you commit capital to it.

We specialize in:

• Water distribution modeling and pressure analysis
• Fire flow analysis for multi-story residential development
• Pump station and booster pump design
• Water storage and pressure zone design
• Site feasibility and utility due diligence

Modern Engineering Solutions, McKinney, Texas. Contact: (214) 833-6748 or mod-eng.com