WSP08301

• File Number: 8273.100.50
• Description: Colorado River Basin Salinity Control - Federal Agency Reports - BOR
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 2/1/1988
• Title: Estimating Economic Impacts of Salinity of the Colorado River - Final Report - February 1988
• Water Supply Pro - Doc Type: Report/Study

40 Estimating Economic Impacts of Salinity...

Clothes washers
Dishwashers

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Certain other types of household appliances
or facilities have been mentioned in one or more
of the earlier studies as having useful life
reduced by salinity. These are: bath tubs,
laundry tubs, sinks, and electric kettles. They
have not been included here because of limited
data or because in the authors' judgment there is
insufficient evidence that salinity can damage
their constituent materials.

Opinions on this point may differ. Those
who may wish to expand the list of household
items subject to salinity damages are referred to
the following data on useful life (expressed in
ranges of years) which are not included in the
computer program developed in this study:

Toilet: 9.6 - 20.0 years (Coe)
Bath Tub: 9.5 - 22.7 years (Coe)
Basin: 12.6 - 18.4 years (Coe)
Sink: 12.2 - 19.4 years (Coe)
Laundry Tub: 10.0 - 17.7 years (Coe)
Electric kettle: 5.0 years (South Australia)
Copper water pipe: 43.78 - 43.82 years
(d'Arge & Eubanks)
Copper wastewater pipe: 48.33 - 60.00 years
(d'Arge & Eubanks)
Plastic water pipe: 48.33 - 60.00 years
(d'Arge & Eubanks)
Plastic wastewater pipe: 42.50 - 53.00 years
(d'Arge & Eubanks)

Regressions on Useful Life of
Household Appliances

Data on useful life of several water-using
household appliances under varying salinity
levels were obtained from earlier studies. These
appliances were: household water pipes,
household wastewater pipes, water heaters,
faucets, garbage grinders, toilet flushing
mechanisms, clothes washers, and dishwashers.
Data on washing machines did not distinguish
between clothes washers and dishwashers in
terms of usefuilife, so the data were used for
both. Data from some studies, when plotted,
were significantly different from the majority of

studies. Therefore a few data sets were selec-
tively omitted on a judgmental basis. Where dis-
crepaneies were found, greater emphasis was
given to data developed from observation, rather
than from interviews with household members.
Where TDS/usefuilife relationships were given a
mathematical formula, as was true in Tihansky's
work, values were calculated through the range
of 200-1200 mgiL.

Data on useful life of household water and
wastewater pipes were based on galvanized iron,
copper, or on unspecified materials. Perhaps be-
cause of this, the data were erratic. It was
decided, for sake of consistency, to use data from
a single study - that of Dennis Tihanskj8 - for
both types of pipes. Tihansky's data were ob-
tained from a variety of sources and were
reduced to the following form of formulas, which
have been modified in notation so that A & B =
constants, m = power e, 2, or \ y = useful life
in years, and t = tds in mgiL:

y = A :t Btm

The special computer program, described in
chapter 3 to calculate regression formulas for
crop yield, also was used to calculate regression
formulas for useful life of water-using household
appliances, and to plot regression curves. Three
regression formulas and curves were calculated
and plotted for each of the remaining household
items, using polynomials to the first, second, and
third power. The regression which gave the best,
i.e., lowest, Goodness of Fit Criterion was
selected for use in this study. The formulas are
as follows, with coefficients rounded:

Water heaters: y = 14.63 - 0.013t + 0.689
(10.S)t2 _ 0.11 (1O-8)t3

Faucets: y = 11.55 - 3.05(10.3)t

Garballe grinders: y = 9.23 - 3.87(1O"3)t +
1.13(1O-6)t

Toilet flushing mechanisms: y = 11.48-
6.29(10.3)t

28.rihansky, "Damage ASSCSliment of Household Water Quality," p. 908.