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City explores simple solution for multi-million dollar problem

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Written by Kara Vaught Saturday, 07 July 2007

Pflugerville residents can potentially save the city budget $15 million by spending a few moments with their water softeners.

Last year, the City of Pflugerville changed both its water supplier and the method in which it receives water. Instead of relying on water from the often-low Edwards Aquifer, the city created Lake Pflugerville, filling it with water from the more reliable lower Colorado River.

The switch, now more than half complete, resulted in a year without restrictions on lawn watering, which had recently become common due to droughts, said James Wills, Pflugerville’s acting director of utilities.

In addition to a larger supply, the city also gained naturally softer water in the switch. However, many household water softeners are still set to treat very hard water, sending excess amounts of the salt used in the softening process into the city’s wastewater, Wills said.

The city’s new wastewater treatment plant, expected to be complete by the end of the summer, lacks a reverse osmosis system to remove salt from treated water before it is released into Gilleland Creek, which feeds the Colorado River. The Texas Commission on Environmental Quality regulates levels of dissolved solids, including salt, which can be present in treated water because high levels of those substances are harmful to water plants and animals.

To remove the extra salt, the city would need a large-scale version of RO units many homes employ to treat drinking water. Its price: $15 million.

The expense is unnecessary, Wills said, if the city can successfully lower wastewater sodium levels by educating residents about the correct programming of water softeners. The deadline is 2009, when the city must renew its permits with the state and prove its wastewater has acceptable levels of dissolved solids.

The city has an ongoing information campaign to alert residents to check their water softeners, and it appears to be working, Wills said. In two months, the sodium content of wastewater has dropped 33 percent to 800 parts per million. The goal is 450 parts per million.

“This is something we can control with the citizens’ help, and that way we can use that money for something else,” Wills said.

Soft vs. hard water

Ground water, such as the Edwards Aquifer, is hard because calcium and magnesium dissolve into the water as it flows underground. Surface water, such as that in the Colorado River and Lake Pflugerville, absorbs less of these minerals and is softer as a result.

“If you take a glass of water and pour in sugar and it dissolves, the sugar is still there,” Wills said. “It’s the same with well water; it has a lot of solid chemicals dissolved in it.”

The levels of total dissolved solids in groundwater can be between 380 and 420 parts per million, while surface water is between 120 and 160, Wills said.

Setting a softener

Hard water takes a toll on household appliances, on which dissolved solids are deposited. Evidence of hard water can be seen in corrosion of metal fittings on sinks, bathtubs and hoses. Refrigerator manufacturers do not recommend hooking an ice maker to a hard water source.

Thus, many homeowners choose to install water softeners. The devices work by exchanging hard calcium and magnesium for non-hardening sodium.

In the softening process, water flows through small polystyrene beads coated with sodium. The beads easily release sodium particles, but calcium and magnesium are drawn to the beads like magnets. Thus, hard minerals are left behind and the softer water flows on for household use.

Before the city switched water sources, Pflugerville residents treated hard water by setting softeners to release 22 to 24 grains of sodium per gallon of water, Wills said. For treating water from the Colorado River, softeners should be dialed down to release six to eight grains per gallon.

Which water where

Depending on the location, water flowing from a faucet in Pflugerville could be coming from Lake Pflugerville, the Edwards Aquifer or a mixture of the two.

Residents east of Toll 130 receive naturally softer water from the lake, and therefore should set their water softeners to use far fewer grains of sodium per gallon of water.

Residents nearest the west side of Toll 130 also receive lake water, but lake water is mixed with aquifer water for homes in the vicinity of Railroad. The city’s existing pumping stations are not powerful enough to deliver lake water past that point, so residents on the west side of the city still receive hard aquifer water. A new pumping station is planned to close the coverage gap, but a location for it has not yet been chosen, Wills said.

The city has recommended water softener settings for subdivisions based on samples taken at each location. However, some areas within the city are not on the city water system because the lines there are owned by other water companies.

Residents should contact the city at 251-3076 with questions about water or softener settings.

How water softeners work

Water flows through small polystyrene beads coated with sodium. The beads easily release sodium particles, but calcium and magnesium are drawn to the beads like magnets. Thus, hard minerals are left behind and the softer water flows on for household use.