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1.10 Water Systems Management 23
proximity, and abundance of suitable water sources; need for water treatment; availability
and price of labor and materials; size and construction conditions of the system; habits of
the people; and characteristics of the areas served. Wide differences in these factors make
for much variation in initial costs. For communities in excess of 10,000 population, replace-
ment costs in North America lie in the vicinity of $1,800 per capita (for 2008 price levels;
for other years multiply by the ratio of an applicable utilities price index; see Appendix 16),
with much of the investment in small communities chargeable to fire protection.
Of the various system components, collection and transportation works cost about a
fourth, distribution works slightly less than a half, purification and pumping works about a
tenth, and service lines and meters nearly a sixth of the total. The initial cost of conven-
tional water filtration plants is about $1,500,000 per MGD ($396,000 per MLD) capacity,
varying with plant size as the two-thirds power of the capacity. The cost of water treatment,
excluding fixed charges, lies in the vicinity of $420 per MG ($111 per ML), varying with
plant output capacity inversely as the two-fifths power of the daily production. Including
interest and depreciation as well as charges against operation and maintenance, water costs
$300 to $3,000 per million gallons ($80 to $800 per million liters) and is charged for
accordingly. As one of our most prized commodities, water is nevertheless remarkably
cheap—as low as 12 cents a ton delivered to the premises of large consumers and as little
as 24 cents a ton to the taps of small consumers.

EXAMPLE 1.6 ESTIMATION OF WATERWORKS COST
Roughly, what is the replacement cost of a conventional filtration plant and other waterworks for
a city of 100,000 people and what is the average plant flow?
The following conditions are assumed:
a. A per capita first cost of $1,500 in 2008.
b. 30% of the first cost is to be invested in the collection works, 10% in the purification
works, and 60% in the distribution works.
c. A water consumption rate of 150 gpcd (568 Lpcd) for the city.

Solution 1 (U.S. Customary System):
1. Assuming a per capita cost of $1,500, the total first cost is 1,500 100,000
$150,000,000.
2. Assuming that 30% of this amount is invested in the collection works, 10% in the purifica-
tion works, and 60% in the distribution works, the breakdown is as follows:
• Collection works 0.3 150,000,000 $45,000,000.
• Purification works 0.10 150,000,000 $15,000,000.
• Distribution works 0.60 150,000,000 $75,000,000.
3. Assuming a water consumption rate of 150 gpcd, the total water consumption of the city is
150 100,000 gpd 15 MGD.

Solution 2 (SI System):
1. $1,500 100,000 $150,000,000
2. Same as Solution 1.
• Collection works 0.3 150,000,000 $45,000,000.
• Purification works 0.1 150,000,000 $15,000,000.
• Distribution works 0.6 150,000,000 $75,000,000.
3. Assuming a water consumption of 568 Lpcd, the total water consumption of the city is
568 100,000 Lpd 56.8 MLD.