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Plumber: Wastewater worries

Question: I'm building a new house and have two questions about the wastewater drain systems. First, do the new 1.3-gallon-per-flush toilets have enough water capacity to carry the wastewater (especially toilet paper) all the way to the main sewer line? Also, if the discharge line has too much pitch, could that cause the water to "run away" from the waste materials in the line?

Any help will be appreciated since I'm now working with my plumber on the plans for my dream home. Thanks! — Frank in Oregon

Answer: I like the way you are building your new home. It seems that you're breaking down the systems (plumbing, electrical, heating, etc.) into separate categories, and going over your concerns about each system with the subcontractors. This is what a good general contractor will do with all their subs to avoid problems down the road.

As far as the first question, about water flow with the new high-efficiency toilets, I have spoken with several engineers from major toilet manufacturers. They studied and tested such concerns in the design labs before putting the new HETs on the market.

I cannot tell you about specific testing that has been done, since it's usually private information that's gathered in these test labs. But I can tell you that when a new HET hits the market from a major manufacturer, that toilet is ready to do the job in the "real world."

On today's market, I've seen single-flush "gravity" toilets using 1.3 gallons per flush, and "air-assisted" power-flush toilets that use only 1 gallon per flush. Right now, they seem to be the current HET water-use standards that I'm familiar with. Other popular HET options include "dual flush" models that use 1.6 GPF for solids and 0.8 GPF for liquids.

So if you are overly concerned about the amount of water used in flushing solids in your drains, a dual-flush toilet can be a good option for you to discuss with your plumber.

For the second part of your question: yes. Make sure your plumber uses only the correct size lines and sticks to the proper pitch in your drains according to local codes. Too much pitch can cause the water to "run away" from the solid materials, leading to possible clogs.

Question: Ed, thanks for being here for all us armchair plumbers. Your information is very helpful! My wife and I are building our retirement cabin and are at the stage for electrical and plumbing. What should we install first for the best results, the electrical or the plumbing systems? — Steve in New York State

Answer: Building a home is a process of breaking down each system and/or part of the process, then putting it together like a big puzzle in the order that works best for the builder. So, I cannot tell you what system should come first or second, because every home can have different circumstances.

What I can tell you is that I like to install large ridged components like drain lines or air ducts first, since there is not a lot of "wiggle room" with those materials, while electrical and cable wires are very forgiving and flexible materials for working around obstructions.

So, I tend to install those types of flexible materials toward the end of the process. Recently, PEX piping for water lines seems to be catching on for this same reason. It takes the traditional hard copper piping issues out of the equation, since PEX piping basically runs like flexible wire lines.

Bottom line: There does not necessarily have to be a "best" first install system, just an installation system that works "best" for you!

Master Contractor/Plumber Ed Del Grande is known internationally as the author of the book "Ed Del Grande's House Call" and for hosting TV shows on Scripps Networks and For information, visit or write Always consult local contractors and codes.