Corpus Christi practically running out of water has highlighted just how scare a resource drinking water can be and how we should look to conserve it wherever we can. Key issues with this include water conservation and water reuse. There are several developments in the greater Houston area who have undertaken practical steps to protect the water supply for their residents and embraced water reuse through the introduction of Purple Pipe, reclaimed water systems. These systems have been introduced in the Houston area as a part of master planned communities but also as retrofits for existing communities, demonstrating that, in both new and existing development the use of reclaimed water for irrigation can be cost effective, if not profitable for residents.
A successful water reuse system needs a source of supply, a distribution system and an end user, regardless of whether it is service a new or existing development. The requirements are the same but the costs can be different. The Bridgeland Development has, perhaps been the greatest advocate for purple pipe systems in new development, utilizing their lake systems to capture and store a mixture of rainfall, reclaimed water and Little Cypress Creek to provide water through a non-potable distribution system to irrigate the common areas such as parks and esplanades, saving over $1 million annually in potable water usage.
Cinco Ranch MUD 1 has demonstrated that reclaimed water can be effectively adopted for an existing mature community, successfully identifying the three key elements required for a project: A source of water, a method of distribution and an end user. They use reclaimed water from the existing central wastewater treatment plant, combined with about 10 miles of non-potable water distribution piping to provide irrigation to medians along many of the major thoroughfares and the local golf course resulting in the saving of almost 290 million gallons of drinking water for residents. This represents useable water for 2,650 homes ensuring water is available to residents and avoiding pumpage fees associated with the Surface Water Conversion of west and north Houston. These pumpage fees and rebates from the regional water authorities have resulted in a saving of $1.6 million on residents water bills, against a project cost of $12.7 million demonstrating how quickly the project pays off financially, regardless of any sustainability or altruistic goals for the project.
Cinco Ranch MUD 1 has been so impressed by the results to date they are currently investing an additional $14.7 million dollars to expand the purple pipe system with another 8.5 miles of purple pipe and modifications to a second wastewater plant as an additional source of non-potable water.
Fort Bend Regional Water Authority offers a rebate of $0.75 per 1,000 gallons of reclaimed water with similar rebates offered by the West and North Harris County Regional Water Authorities in addition to the elimination of the $4.55 per 1,000 gallons of groundwater pumped meaning the district is saving about $85,000 to $125,000 per month for a total saving of about $1.5 million last year (2025). Comparing this to the installation costs you can see that the rate of return is fairly short.
Reclaimed water currently reclaims just over 25% of their central WWTP discharge and has to treat the reclaimed water to Type 1: High quality standards as per the TCEQ rules (30 TAC Chapter 210). This is because of the possibility of public contact associated with the end users, central medians of thoroughfare roads, green belts and golf courses, all of which could see the public coming into contact with the irrigation systems as they are running.
The distribution system needs to be separated from the potable water system with physical interconnection strictly prohibited, minimum spacing requirements between pipe systems, color coding of pipe and signage requirements to ensure there is no cross contamination. This is where the slang terms, Purple Pipe, comes from with the color purple used to denote reclaimed water systems. In addition, there are testing requirements with sampling frequency outlined by the TCEQ.
The idea is gaining traction with a number of presentations at conferences such as AWBD and specific Water Reuse Conferences held around Texas each September. The idea is gaining traction and the benefits both measurable and substantive. The key numbers coming out of Cinco Ranch are: Reclaimed water at $0.95 per 1000 gallons vs Potable water at $6.50 per 1000 gallons. These savings have got to be worth looking at.
