Expansion Pathways

The Growth Challenge

The Texas Water Backbone, even at ultimate capacity, represents a critical first step rather than a complete solution. Understanding the gap between what the Backbone provides and what Texas will need enables strategic planning for expansion.

The Numbers

The gap grows from both directions: demand increases while existing supply decreases.

What the Base Backbone Provides

The base Backbone is essential but insufficient. It buys time and establishes infrastructure for expansion.

Municipal Demand Growth Focus

This analysis focuses on municipal demand growth—the fastest-growing and highest-value water use:

The I-35 corridor—precisely where the Backbone delivers—accounts for the majority of municipal growth.

Pipeline Capacity Limits

Before exploring expansion scenarios, we must acknowledge physical constraints. However, it’s important to understand how the buffered network design changes the capacity equation compared to a traditional linear pipeline.

Linear vs. Buffered: Why It Matters

A traditional linear pipeline must maintain continuous flow velocity across its entire length. The buffered network proposed for the Backbone operates differently—water moves through 5 hydraulically independent segments, “resting” in ASR buffers between segments.

Key insight: Buffers decouple capacity from velocity. The system can pump at optimal velocity most of the time, using buffer storage to handle peak demands rather than requiring sustained high-velocity flow.

Single Pipeline: Linear vs. Buffered Capacity

The buffered network can push 70% more water through the same pipe because:

• Each segment operates at optimal (lower) velocity
• Buffers absorb demand peaks without requiring velocity spikes
• 24/7 steady pumping fills buffers during low-demand periods
• Segments operate independently, avoiding system-wide hydraulic constraints

Dual Pipeline Buffered Network

With dual pipelines in the buffered configuration:

The dual-pipeline buffered network can sustainably deliver ~800,000-1,000,000 AF/year—significantly more than a linear design’s ~580,000 AF/year limit.

Maximum Corridor Capacity

Could we add more pipelines to the proposed corridor? The 200-foot right-of-way was designed for dual pipelines, but with ROW expansion could accommodate more.

Starting from the recommended dual-pipeline baseline ($11.15B):

Why adding later costs more:

Physical constraints still limit the proposed corridor:

Even with the buffered network’s efficiency gains, the corridor has an absolute ceiling of approximately 1.5-2.0 million AF/year with maximum pipeline expansion—constrained as much by source production as by pipeline hydraulics.

Why Brackish Integration Helps

Brackish facilities inject water at points along the corridor, not at the coast. This water doesn’t require full 420-mile transmission:

Distributed sources reduce pipeline bottleneck pressure. The 234,000 AF of brackish water requires only ~150,000 AF-equivalent of pipeline capacity.

Effective Corridor Capacity

This fits within dual pipeline limits (580K AF max) because brackish sources are distributed along the route.

What This Means for Expansion

The buffered network significantly extends what the corridor can deliver. However, even at maximum build-out (~1.5-2.0M AF/year), the corridor addresses only 25-32% of the projected 6.3M AF gap.

For a deeper analysis of why Texas cannot build its way out of the water crisis, see The Math.

Conservation Foundation

Before calculating infrastructure needs, this analysis assumes municipalities achieve 80% of their State Water Plan conservation targets.

Conservation Contribution

The 80% Standard

Why 80%? It represents achievable targets without extraordinary measures:

Net Demand Growth After Conservation

Expansion Scenarios

With net demand growth of 2.0M AF/year, what infrastructure is needed to meet 20%, 40%, and 60%?

Scenario Summary

The current plan with brackish integration already exceeds 20% of net growth. Scaling to 40% and 60% requires strategic expansion.

20% Scenario: Already Achievable

The fully-built Backbone with brackish integration meets this target:

Investment: $13.9B (base Backbone + brackish)

Status: Covered by current planning documents.

40% Scenario: 800,000 AF/year

Meeting 40% of net demand growth requires modest expansion beyond current plans.

Options to close the 66,000 AF gap:

Recommended 40% configuration:

Additional investment beyond current plan: ~$320M Total investment (40% scenario): ~$14.2B

60% Scenario: 1,200,000 AF/year

Meeting 60% of net demand growth requires substantial expansion across multiple sources.

Expansion strategy for 466,000 AF:

Recommended 60% configuration:

Additional investment beyond current plan: ~$3.5B Total investment (60% scenario): ~$17.4B

Source Options

Additional Seawater Desalination

The Gulf Coast has capacity for additional facilities:

Ultimate seawater capacity: 500 MGD (560,000 AF/year) with current plan; expandable to 900+ MGD with additional facilities.

Expanded Brackish Development

Beyond current plan, additional brackish capacity exists:

Produced Water Treatment

The Permian Basin generates 1+ billion gallons/day of produced water. Even modest capture creates significant supply:

Indirect Potable Reuse

Major utilities are developing reuse programs that could integrate with the Backbone:

Reuse integration requires:

• Treatment to potable standards
• Blending protocols with Backbone water
• Public acceptance programs

Investment Summary

Total Capital Requirements

Phased Investment Timeline

Cost-Effectiveness Comparison

The Remaining Gap

Even at 60% scenario (1.2M AF/year), Texas still faces a supply gap:

How is the remaining 40% addressed?

The Backbone system, even fully expanded, is not the sole solution—but it is the essential foundation that makes other strategies viable.

Key Findings

The Path Forward

The Backbone architecture is designed for expansion. Each buffer, each connection stub, each power tap creates optionality for future capacity additions.

The question is not whether to build expansion capacity, but when—and the Backbone ensures Texas has the infrastructure to scale when the time comes.