| Practically all municipalities with populations of more | | | | required to handle. |
| than 2,500 maintain systems of sewage disposal | | | | Combination public sewers are the oldest variety of |
| consisting of a sewage treatment unit of either | | | | the three types of sewers and they are required to |
| activated sludge or filter type and a system of | | | | carry storm and sanitary wastes to some safe |
| sewers installed below the streets by which the raw | | | | terminal. These sewers are obsolete, but still make |
| sewage is conveyed to the disposal plant or unit. | | | | up a large part of public sewage systems. Rain water |
| In recent years health authorities have realized more | | | | should be carried to some terminal not associated |
| than ever before, that the source of drinking water | | | | with the disposal plant, because large quantities of |
| must be protected against contamination caused by | | | | water affect operation and necessitate an |
| the discharge of large volumes of domestic and | | | | exceptionally large installation to handle it. |
| industrial sewage into it. With the aid, in some | | | | Water from your bathroom, from either the toilet or |
| instances, of federal grants, this phase of sanitation | | | | the bathtub can go here. Bathtub paint tends to |
| has progressed rapidly within the last ten years. | | | | cause some problems with drains so make sure you |
| The installation of public steam enclosures doesn't | | | | keep up with glazing. |
| necessarily involve a plumber. Residential steam | | | | Sanitary sewers are those which are required to |
| showers and steam rooms, however, are a new field | | | | carry domestic sanitary wastes only. All rain water |
| into which he may easily be fitted. As far as the | | | | must be excluded from them. The terminal of these |
| installation of public sewers and disposal units is | | | | sewers is a modern sewage disposal plant. |
| concerned he does not play a very active part. | | | | Combination and sanitary sewers generally are placed |
| The work, especially that of constructing concrete | | | | about ten feet under the street grade and usually |
| and vitrified clay sewers, usually is done by | | | | are found below the center line of the street. |
| semi-skilled labor or by workers trained in this field. | | | | Storm sewers are a comparatively new installation, |
| The plumber does, however, use the public installation | | | | made necessary because of sewage treatment. |
| as a terminal for private plumbing systems, and it is | | | | These sewers are made to carry only storm water |
| quite necessary that he should be familiar with the | | | | and may terminate at any natural drainage area. |
| public system, at least to the extent of being | | | | Although these are meant for large quantities of |
| well-informed. | | | | water, you cannot dump water from your swim spa |
| It is quite essential, too, that he know the various | | | | or hot tub, because the hot tub chemicals need to |
| types of sewers and the principles involved in | | | | be disposed of properly. This type of system drains |
| construction and operation of a modern disposal plant. | | | | into natural reservoirs and any water that did not |
| There are three types of public sewers, each | | | | come from the sky is contaminated. |
| classified according to the kind of wastes it is | | | | |