IOWA ACADEMY OF SCIENCE 
137 
from a study of the municipal water systems of the state. The following 
figures are from the Underwriters’ Hand-book of Iowa, in which are given all 
the towns of the state with their populations and their means of fire protec- 
tion. The populations are taken from the last census, though the edition of 
the book is for 1907. 
In going over the list the following facts appear. There are 324 cities and 
towns having water systems, including stand-pipes, street mains and fire taps. 
Towns having systems for fire protection only are not included. Of this num- 
ber six have as their sources of supply lakes, or natural or artificial ponds; 
twenty-four have water from rivers, and 294 get their water from wells. It 
appears further that the urban population in towns having water systems are 
supplied as follows: 
Prom lakes and ponds. 21,000 
Prom rivers .......... 341,000 
Prom wells 534,000 
It follows that well water supplies about 60 per cent of the dwellers in such 
towns But, this is only a part of the truth. The inhabitants of such towns 
are a comparatively small minority as compared with the whole population of 
the state. There are many large towns without water systems. The people of 
these towns and the whole rural population are dependent upon wells of one 
sort or another. Taking this fact into account it follows that about 84 per cent 
of the whole population are dependent upon ground water. 
There is much reason to expect a greater proportionate development in the 
use of ground water, and water from deeper sources. Though there are many 
towns of 150 to 300 inhabitants that have water systems, there are also many 
of 500 to 2,000 people that are yet without such systems. They will be forced 
to provide such supplies in the near future. The indications are that many 
towns have installed water systems more or less temporary and to meet the 
then existing needs, whether this temporary character was intentional or not. 
There is observable a very general tendency to extend well systems and to put 
down deeper wells as the towns have grown. It is interesting also to note the 
tendency to provide unfailing water supplies on the farms. Iowa is getting to 
be a state of very large live stock interests. Stock must have water, and 
something better than the shallow well, located very likely in some draw, only 
a few feet deep and provided it may be with only a hand pump, has become 
a necessity. The result is that farm wells 100 to 500 and even 1,000 feet In 
depth are becoming very numerous, and it is very probable that with the in- 
creasing need of plenty of good water, and also the increasing wealth of 
farmers in Iowa such farm wells will become very general. 
In the former paper referred to, mention was made of the corrosion of well 
casings by hard waters. Several instances are on record where casings or 
parts of them have been taken out of the wells and found full of holes due to 
pitting. There is evidence that this is very general in wells having hard 
waters, and though no very accurate data have been collected the probability Is 
that ordinary iron tubing in wells having quite hard water will be eaten 
through in from five to ten years. The following is an interesting example in 
a well in the southern part of the state and in a particular locality where 
the upper water is very highly mineralized. The well was drilled in 1904 to 
