Issue 75 November 17, 2002

Cross Connections

In Rex Cauldwells book "Inspecting A House" the appendix titled "Cross Connections" relates the story of the Prince of Wales:

"If I could not be a prince, I would be a plumber."

"The year was 1871 and the Prince of Wales is lying on his deathbed at Londesborough Lodge. Already dead was his groom and his good friend the Earl of Chesterfield. A plumber was called in to find if there was a problem with the water. There was. A "cross-connection" was found from the sewage line to the drinking water. In his gratitude for the plumber saving his life, the prince uttered this famous line."

Cross connections in a home can be deadly not only to you, but to your neighbors. Why is it then when I point one out everyone in the room looks at me as if I have lost my mind? Proper plumbing practice is much more than supplying a source of water and a method by which waste can be carried away from your home. Its about your health and welfare. In today's world health related issues involving the plumbing systems in our homes appear to be taken for granted. We assume the water in our homes is safe to partake off and have little fear that it may make us sick or even worst, bring about our demise. The most common health related issue involving the plumbing systems in our home found by the home inspector is probably "cross connections." 

So, what is a cross connection? A cross connection is any situation where potentially potable water may come into contact with nonpotable water. Potable, what is potable? It simple means fit to drink, or fit for human consumption. We assume the water entering and circulated to the fixtures in our homes is potable and that leaving our home from the fixtures to be nonpotable. But, what happens when unintentionally the potable comes in contact with the nonpotable? Contamination, and this contamination can make us very sick. The most common cross connections in homes can contaminate the water supply with sewage, fertilizer, insecticides and herbicides to mention a few, but they are not the only possibilities. 

The most common cross connection I observe in today's homes involve hand held shower and sink (hair wash) sprayers. The second is faucets inside of antique tubs and foot wash faucets below the rim of the fixture. Remember, potable and nonpotable water should never come in contact (touch). Water held inside of a basin, sink, tub, shower stall, etc., is considered to be nonpotable. There must always be space maintained between the potable water source and this nonpotable water to prevent possible contamination of the water supply. I know what you are thinking, when the potable water is running, it is in contact (touching) the nonpotable water. You are correct, but there is a positive flow which prevents the water supply from becoming contaminated. The water is moving away from, not toward the source. Contamination occurs when this flow is reversed. If there is an adequate gap between the water source and the source of the potential contamination, contamination of the source is prevented. But, if this gap does not exist, the resulting contamination can be disastrous. Imagine that contaminated water somehow gets from one house into the surrounding water system, how many people could be affected? Do you think this is something you should be concerned about? 

How does this occur? Lets use the shower sprayer as an example. You are tie-dying shirts in the bathtub, or treating your dog. The sprayer is on and lying in the tub. unbeknownst to you, there is a break in the main water supply down the street. This causes a suction drawing the contents of your tub into the outside water supply. The same thing could occur if the water faucet were below the rim of the tub or sink and the water is filled above this faucet. What about the little lady next door spraying pesticide on her flowers with a garden hose having a large pesticide container attached. If you don't think this is a serious concern, you should talk with the people who have become sick from just such an event, or the communities where systems have become so contaminated that the pipe under the streets had to be removed and replaced because decontamination could not be accomplished. Cross connections are a serious concern and should be corrected immediately. Don't think it could happen at your home? Do you remember ever having dingy muddy water from a main line break? That's it!!

So, what is acceptable. To start with, no water supply faucet should be below the rim of the receptacle (sink, tub, shower curb, etc.). A handheld shower sprayer should have a hose length such as not to allow the sprayer to fall below the rim of the tub or there must be a backflow valve (vacuum breaker) in the line. All hair wash sink hand held sprayers and exterior hose bibs should have backflow valves. Ideally there should be a duel-check valve (backflow valve) on the incoming main water supply line to prevent contamination of the public water supply by not allowing water to flow back into the street lines. 

Common Cross Connection Points:

Hand held shower and sink hair wash sprayers
Heat pump/air conditioner condensation lines
Faucets below the rim of the receptacle
Exterior hose bibs
Hose on laundry sinks
Dog-wash stations
Water-conditioning systems (discharge line connected directly to the waste system)
Supply pipe from spring-fed water source
Well-seal problems

Next time the home inspector uses the words "cross connection" you can respond with, yes that needs to be corrected immediately instead of that "what the heck is he talking about" look. 

Thought for the week
 
"A real friend is one who walks in when the rest of the world walks out."