How to Identify the Source of a Water Leak in a Commercial Building

Unwanted water in buildings can cause staining, degradation of building materials, and an environment for mold to grow. Water can come from a few possible sources in a building, including drinking water, sewer plumbing, a leak starting at the exterior of the building envelope, ground water, and a pool if the building has one. The water chemistry will be different at each of these locations, which makes identifying the source of the leak possible. The location of the leak is also important in identifying the source.

To determine the water chemistry, ion chromatography is used to identify anions present in the water. Ion chromatography separates each ion by the ionic interactions of each analyte with an ion-exchange column. After separation, each ion concentration is determined by measuring the response of each analyte with a conductivity detector. Seven anions common to water (fluoride, chloride, nitrate, sulfate, nitrite, bromide, and phosphate) are analyzed, and the concentrations of each are determined. The water chemistry is determined for the leak water and each of the possible sources of the water.

Chromatogram showing the separation of seven anions in a reference standard.

After determining the concentration of each ion, the source of the leak can be identified by the anion levels being consistent with one of the possible source waters. Sometimes leaks can come from more than one source, which will change the concentrations of the ions in solution. As well, leak water often migrates through and over concrete and other building materials, and can pick up ions along the way. These leak waters can be identified by comparing relative ratios of anions in the leak water versus the possible source waters.

For more information contact Matt Anderson at 847.306.9240 or manderson@materialsanalyticalgroup.com.

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Unwanted water in buildings can cause staining, degradation of building materials, and an environment for mold to grow. Water can come from a few possible sources in a building, including drinking water, sewer plumbing, a leak starting at the exterior of the building envelope, ground water, and a pool if the building has one. The …

Is My Water Corrosive? Is My Water Scale Forming? How Langelier Saturation Index Measures How Aggressive or Scale Forming Water Is

Langelier Saturation Index (LSI) is a calculation that uses the data of multiple analyses to estimate how corrosive or scale-forming a water is. The chemistry of the water is analyzed, as well as the environmental conditions determined, to evaluate how likely the water would be to corrode or form a scale in pipes. LSI is essentially a measurement of the saturation of calcium carbonate in the water. If the water is over-saturated with calcium carbonate, minerals will precipitate out of the water, and the water will be scale-forming. If the water is under-saturated with calcium carbonate, it will dissolve minerals from the pipes, causing the water to be corrosive.

Water was determined to be corrosive and the cause of the pipe corrosion for this project.

The tests performed to calculate the LSI of a water include pH, calcium hardness, total alkalinity, and total dissolved solids. The temperature of the in-service water is also used in the calculation.

The calculation is as follows:

where: pH is the measured pH of the water
pHs is the calculated saturation pH of the water

The saturation pH (pHs) is calculated as follows:

where: pK’2 is the negative log of the activity constant K’2

pCa2+ is the log of 1 / the concentration of Ca2+

pK’s is the negative log of the activity constant K’s

pCa2+ is the log of 1 / the concentration of Ca2+

Alk is the alkalinity concentration in moles / liters

ym is the activity coefficient of the monovalent ions

These variables are all determined from the analyses performed and then entered into the calculation to determine the LSI. LSI values range between +4 and -5, where positive values would indicate the water is likely to form a scale, and negative values would indicate the water is likely to contribute to corrosion of the pipes. An LSI value of 0 would indicate the water is neutral and unlikely to promote corrosion or formation of scale. An LSI of -0.5 would indicate the water is slightly corrosive, but would not be scale forming. An LSI of 0.5 would indicate the water would be slightly scale forming, but not likely corrosive. As LSI decreases, the potential for corrosion increases. As LSI increases, the potential for the formation of scale increases.

Langelier Saturation Index testing can be performed at the Materials Analytical Group laboratory. For more information contact Matt Anderson at 847.306.9240 or manderson@materialsanalyticalgroup.com. And for 15% off our services, let us know you have been reading our articles before receiving your invoice.

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REFERENCES

Inspectapedia. (n.d.). Inspectapedia. Retrieved from Langelier Saturation Index: https://inspectapedia.com/water/Langlier-Saturation-Index.php

Labrador, G. o. (n.d.). Calculation of the Langelier Index. Retrieved from Deparment of Environment and Conservation: https://www.mae.gov.nl.ca/waterres/quality/drinkingwater/pdf/calculation_langelier_index.pdf

LennTech. (n.d.). Langelier Saturation Index Calculator. Retrieved from LennTech: https://www.lenntech.com/calculators/langelier/index/langelier.htm

Langelier Saturation Index (LSI) is a calculation that uses the data of multiple analyses to estimate how corrosive or scale-forming a water is. The chemistry of the water is analyzed, as well as the environmental conditions determined, to evaluate how likely the water would be to corrode or form a scale in pipes. LSI is …