This section is from the book "Plumbing Problems", by The Sanitary Engineer. Also available from Amazon: Plumbing Problems, or Questions, Answers and Descriptions Relating to House Drainage and Plumbing.
Q. I find it is very common to connect overflows from tanks with soil-pipes and leaders, putting a trap at some point, which, however, has no means of being kept supplied with water, as the overflow is usually above the tell-tale and hence this trap dries out. Will it suffice to arrange a small pipe from the supply-pipe from pump to connect with the trap and keep it fed at all times, or how would you arrange it?
A. Disconnect the overflow-pipe from the soil-pipe entirely. Under no circumstances should they be so connected.
 
Continue to: