70 DOMESTIC WATER SUPPLIES FOR THE FARM 



Types of well curbs and casings (Continued). 



Type. 



Nature. 



Conditions to which best adapted. 



Cement-lined rock or Brick or stone as above, but laid in and 

 brick. lined with cement. 



Wood. 



Tiles.. 

 Do... 



Heavy iron casings... 



Sheet-iron casings . 



Square wooden boxes in wells over 3 

 feet in diameter; cylindrical curbs of 

 narrow staves in wells under 3 feet in 

 diameter. 



Glazed sewer tile, cement tile and 

 porous terra cotta tile, laid without 

 cement. 



Glazed sewer tile and cement tile with 

 cemented joints. 



Iron pipes, I to 4 inches in diameter, 

 with tight joints. 



Iron pipes 4 to 16 inches in diameter, 

 with snug joints. 



Adapted to shallow dug wells in mate- 

 rials carrying enough water to permit 

 an adequate supply to enter at the bot- 

 tom. Can be used in polluted soils if 

 the contamination is superficial and 

 does not reach to the bottom. 



Can be placed in any shallow well, but 

 are never safe and should never be 

 used. 



Adapted to conditions similar to those 

 of rock and brick curb. 



Same as cement-lined stone or brick 

 curbs, except that it is more applicable 

 to wells of small diameter. 



Adapted to wells of all depths in which 

 water is obtained from a stratum be- 

 low the casing, or from strata be- 

 tween cased sections. Not adapted 

 to strongly corrosive waters. 



Adapted to wells of all depths, in loose 

 material, in which it is desired to pro- 

 cure water from a number of strata. 



In some types of wells for example, in dug, bored and 

 punched wells several kinds of curbing or casing may be used, 

 and the selection should be governed by the sanitary protection 

 or resistance to the entrance of pollution which the casing affords. 

 The advantages and disadvantages of the common forms of curbs 

 and casings are indicated in the tabulated statement below. 



Summary of advantages and disadvantages of different types of well curbs and casings. 



Type of curbing. 



Advantages. 



Disadvantages. 



Rock. 



Brick. 



Cement-lined rock or 

 brick. 



Wood. 



Allows all water to enter, thus utilizing 



all seeps. 



Material often costs little or nothing. 

 As a rule requires little money outlay 



for labor. 



Where uncemented it allows all water 



to enter, utilizing all seeps. 

 Filters out most of sediment. 

 Does not allow small animals to enter. 

 Involves little money outlay for labor. 



Safe from pollution (except that enter- 

 ing at bottom) as long as walls are 

 not cracked. 



Prevents entrance of sediments. 



Prevents entrance of animals. 



Does not impart taste to water. 



Cheap in many localities. 

 Can be used in wells of very small di- 

 ameter. 

 Does not taste of iron. 



Polluting matter enters readily and well 

 is never safe if near sources of contam- 

 ination. 



Affords no filtration and permits dirt 

 and soil to enter. 



Permits entrance of mice and other 

 small animals at top. 



Polluting matter enters readily and 

 well is never safe when near sources of 

 contamination. 



Material costs considerable. 



Utilizes water from bottom only. 



Is unsafe if so shallow that polluting 

 matter can reach its bottom. 



Costs considerably more than unce- 

 mented wells. 



May require skilled labor. 



Swells tight in wet ground, the water 

 either entering at bottom or (after 

 sudden rises) through shrunk portion 

 at top. 



