There are various ways in which it may be necessary to obtain the water supply for a building. The usual course in cities and towns is to employ the Municipal Water Works service. This, of course, settles the supply feature, and the plumber simply provides the house and yard pipe, 5/8-inch or larger main, according to the character of the work. If of lead, the pipe must be of strength according with the pressure. Any of the light-weight grades of lead supply will stand 1,000 pounds per square inch for a short time; and the usual strength used on 50- to 80-pound pressure will not burst under 1,400 to 1,600 pounds when new and unstrained. Under constant pressure, the enormous strain possible from water-hammer, and general deterioration from use, make it advisable to employ pipe which, when new, is 20 times as strong as that necessary to contain the pressure. No attention is necessary as to the strength of zinc-cOated or tin-coated iron pipe; it will stand any pressure ordinarily encountered.

The two general methods of supplying buildings with water are: (1) the direct system; and (2) the indirect or tank system. The direct method, generally employed in cities, places each fixture connected with the supply under the same pressure as the street main, unless a reducing valve is introduced, thus often subjecting the work to needless high pressure and always to the widely varying conditions and quality of service incidental to such use. In the direct system it is good practice, where at all practicable, to pipe and fit the work generally for pressure not exceeding 50 pounds per square inch, and then use a reducing valve to maintain such pressure as is required.

The indirect method is almost always necessarily employed in isolated work; and even where municipal service is available, it is generally better for ordinary domestic purposes. With the indirect system, the connection with the street main is carried directly to a tank placed in the attic, or at some point above the highest fixture, as shown in Fig. 51. The supply to tank is regulated by a ball-cock which automatically shuts off the water when the tank becomes full, and opens and refills it again when water is drawn out. All the plumbing fixtures are supplied directly from the tank, and are therefore under a constant minimum pressure depending on the distance the fixtures are situated below the tank. The tank storage is a matter of great convenience during repairs to street mains, aside from its advantages of uniform pressure, reduced expense of fitting and maintaining low-pressure work, etc.

Fig. 51. Indirect or Tank System of House Supply..

In municipalities where the pressure in the main is not sufficient to carry the water up to the house tank in the attic, and in elevated situations, an automatic, electrically-operated rotary or other suitable form of pump is often installed to lift the water. A screw pump like that shown in Fig. 52 is especially adapted to this use when equipped with an electric motor to start and stop automatically by means of a float in the tank operating an electric switch as shown in the engraving.

Where steam pressure is available, steam-operated pumps are very frequently used, and are invariably arranged for automatic service whether there are engineers regularly in attendance or not. A device that may be attached to steam pumps for this purpose is shown in Fig. 53. When the high-water line in the tank is reached, the float closes a valve in the pump discharge pipe, thus promptly increasing the pressure in it so as to actuate a piston through a pipe connection from the pump discharge to the regulator beneath the piston head. The regulator is shown complete, in detail, partly in section, in Fig. 54. Raising the piston shuts off the steam supply to the pump at the governor valve. When the water line in the tank is lowered, the float falls and the ball valve opens, relieving the pressure in the pump discharge pipe and allowing the steam governor valve to open by the action of the counterweights attached to the lever arm, as shown; and the pump then works regularly until the lifting of the float by the rising water again closes the valve in the pump discharge and repeats the action described.

Fig. 52. Electrically-Operated Pump for Lifting Water to Tank. Automatically Started and Stopped by Means of Float Operating Electric Switch.

Fig. 53. Steam Pump Equipped with Regulator Operated by Float in Tank,.

Securing Automatic Service.

Outside of corporations, the supply may be from an elevated spring or stream, or from wells, cisterns, or other sources below the level of use. If the natural supply is high enough, it may be conveyed into a tank of sufficient height without intermediate apparatus. Tanks inside the dwelling or house are best, ordinarily.

Fig. 54. Steam Pump Regulator (Shown Partly In Section) Automatically Operated by.

Valve Controlled by Float in Supply Tank.

Tanks for cold-water storage are made of various materials and in different shapes and sizes, according to the special uses for which they are required. For indoor use, copper-lined or lead-lined wood-case tanks without safe-pans, and wrought-iron or cast-iron tanks with safe-pans to catch the condensation, constitute the list generally favored by reason of superior fitness. Within limited dimensions, a durable and satisfactory tank-case can be made of heavy, well-fitted, and well-seasoned plank bolted together with iron rods and nuts, as shown in Fig. 55. For large sizes, heavy wood stays with tie-rods one third of the way from each end, are added. With copper linings, but few nails should be used; and they should be so placed as to be covered by the copper, the joints being soldered by soaking the best quality of solder into the seams. The locking of the seams is shown greatly exaggerated in the engraving. Cast-iron sectional tanks, like the form shown in Fig. 56, can be had in almost any size or shape. They are made up of plates planed and bolted together, the joints being made water-tight with cement. The sections are in convenient sizes, so that they can be handled easily, and conveyed without difficulty through small doorways or other openings to any part of the house. These tanks are easily set up, and are practically indestructible. Open and closed wrought-iron tanks, plain or galvanized, are often used, but are not so easily handled; and the larger sizes require to be riveted together and calked in place. Lead-lined tanks are most frequently used for ordinary house plumbing. The linings were formerly wiped-in without exception. Sweating the lead together with a torch flame is however, quite as durable, and is much cheaper. To sweat-in a lining, take the exact length and breadth of the tank, trying at different points to be sure of allowing for any variations. Then cut out the bottom lining just the shape of the tank bottom, one and one-half inches larger each way, less twice the thickness of the lead. This allows three-quarters of an inch to turn up all around; and the bottom will just fit when the side pieces are in place. Mark off the bottom all around, as shown by the dotted lines in Fig. 57; and turn up the edge. With the intersection of the lines A as a center, and the termination of one of them as a starting point, describe the line B, and cut off the corner outside of it. Then work the corner up square without a kink. If the lead is heavy, a little heat will make it work better. After working-up, the lead at the corners will be much thicker than along the sides; this may be needed in stretching out, at some of the corners.