SEWAGE 



275 



To be efficient a trap should remain full of water. The 

 traps, however, occasionally get emptied of water, and 

 then gases may pass up from the sewers. Such gases are 

 offensive in odor and used to be regarded as dangerous 

 to health. It is now realized that these gases do not bring 

 bacteria into the house with 

 them and hence are harm- 

 less although undesirable. The 

 insides of the traps, however, 

 become breeding places for cer- 

 tain kinds of bacteria, though 

 rarely disease bacteria, and may 

 in time become full of them. It 

 is therefore desirable to pour 

 some kind of disinfectant occa- 

 sionally into the bowls and 

 sinks. A weak solution of car- 

 bolic acid, one part to twenty. Fig. 8o. Diagram showing the 

 or a solution of chloride of lime, pri""pie of two kinds of traps 



. separating washbowls from 



one part to twelve, put mto sewers. 



bowls and sinks will disinfect 



the traps. It is also an excellent plan to pour boiling water 



frequently down sinks, bowls, and closets, for this not 



only lielps to clean but helps also to disinfect. 



Leaky sewer pipes in a house are a serious menace. If 

 these are poorly laid, the contents of the sewer may ooze 

 out into the cellar or soil under the cellar and become a 

 source of considerable danger. For this reason it is desirable 

 to have sewer pipes laid where they may be easily inspected. 

 When the pipes are laid above the cellar floor, leaks are 

 more likely to be noticed and to receive attention at once. 



