128 LEAKAGE FROM STREET MAINS 



various purposes as soon as it is turned on. There is ordinarily 

 a demand for the use of the pipe even before it is laid, and there 

 is no time to be used in testing. 



Afterward it is possib e to isolate a certain section of pipe 

 at any time and to find out how much water is going into it, 

 but the amount so found represents both leakage from the pipe 

 and water drawn through the services. 



Making the observation between one and four o'clock in the 

 morning in a residence street, during which time the use of water 

 is presumably very small, gives an indication of leakage, because 

 very nearly the whole flow at that hour is leakage. 



Shutting off the stop-cocks on each individual service adds 

 greatly to the difficulty of the experiment, and also to the value 

 of the results obtained. Even after this is done there remains 

 some uncertainty as to whether the observed loss of water is 

 from the pipe itself or from the service pipes between the main 

 and the shut-off cocks, and it may be that some abandoned and 

 forgotten service pipe with a partially closed end is discharging 

 water to a sewer. 



Tests of new lines before service connections are made have 

 occasionally been possible and some information has been col- 

 lected in regard to them. Such information is useful, but it is 

 hardly to be taken as a guide in estimating leakage from old 

 mains. There are slight movements of the pipes at times 

 because of temperature changes and for other reasons, and these 

 tend to open joints, and there is more likelihood of leaks in the 

 joints of old pipes than is the case with new ones. 



On the other hand, one engaged in the water-works business 

 has occasion to see from time to time pieces of pipes in services 

 under pressure and joints between successive lengths of pipe. 

 Such occasional inspections do now and then show leakage. 

 The frequency with which joints that leak are found depends 

 most of all upon the conscientious care with which the pipes have 

 been laid and the joints caulked. If the work has been badly 

 done, leakages may be common. It is the writer's experi- 

 ence that in well-laid old systems leakages from pipe joints are 

 not common. The great majority of joints that come to his 



