The Golden State: Where & How to Live, Secure, Visit, Enjoy and Thrive in California

How To Design And Install Plumbing

A leveling instrument can be used to advantage. Very often the house sewer is installed before the basement floor grade has been laid out. Then it becomes necessary to make a general survey of the contour of the soil relative to street grade or established bench marks.The plumber cannot rely on hit-and-miss methods to establish the pitch of the sewer.

Uncertain procedure often results in house sewers being needlessly above basement floors. The usual pitch of a house sewer is not less than 1/4 inch to each foot. However, should it be necessary because of building difficulties, less pitch per foot may be allowed.

Additional Grade. It is not unusual to pitch a house sewer more than 1/4 inch per foot. This practice becomes necessary when the house drain outlet is sufficiently high. The general procedure under these circumstances is to grade the part of the house sewer between the main sewer and the curb not more than 1/4 inch per foot and the remainder of the sewer, between the curb and the house drain outlet, not more than 1/4 inch. This practice overcomes the necessity of deep, costly digging and adds to the installation materially. Fig. 46.

Additional grade can also be made with the use of two curves or 1/8 bends, see Fig. 47. This is the most practical method of obtaining grade.

Size of the House Sewer. The size of the house sewer, for ordinary residence installation, has been established by sanitary authorities whose compilations are the result of installation tests and mathematical conclusions. Standard practice requires that the minimum size of a house sewer constructed of clay pipe be not less than 6 inches in diameter. It has been found that a sewer of this kind has ample discharge capacity and serves the installation adequately.

If cast-iron pipe is used, the size of the sewer can be reduced to a 4-inch diameter pipe, provided local authorities sanction this installation. In most instances a 6-inch diameter pipe is installed from the main in the street to the curb line and then may be reduced to a 4-inch pipe to its connection with the house drain. This practice averts the necessity of breaking up the street should additions be made to the original plumbing installation.