How many clean outs do I need

I have a sewer pipe that runs out the back of my house to the ally way. There are two cleanouts in line space about 2 feet apart and 2 fee off the house and another third clean out 20 feet out from the first two toward the alley, for a total of 3? I am pouring a patio slab that will cover the first two? Do I need to retain access to one, two, or all three...
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Mesquito Creek wrote:

Check with your city or the sewer utility. You *may* live in a part of the country where "house traps" were commonly used (that's what the 2 next to the house sound like). If so, they're not cleanouts but necessary access to the trap.
The 3rd may be a vent. If so, there could be a real problem covering or extending it into the patio. I can't guess from here; find out for sure locally.
Jim
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Many places require a clean out access every 50 ft or less. This is more important now than it used to be. When our uninformed Congress decreed low flow rate faucets the flushing that occurred in low pitch drains was imperiled. The need to mechanically clean out drains, particularly if there's a garbage disposal, has become a much more frequent occurrence. Plumbers love it.
RB
Speedy Jim wrote:

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I thought that everyone knew to flush twice with those water saver (line clogger) toilets.
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Christopher A. Young
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Could you describe the function of "house trap", please? It's a term I don't know.
TB
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Tom Baker wrote:

Because we don't have a "National" plumbing code, practices differ everywhere. 100 years ago, it was believed that the sewer lateral into the house needed a trap to prevent gases from the street sewer entering the house. Others argued, just as vehemently, that the house trap should be forbidden and that the vent stacks on all the houses on a street should be counted upon to vent the street sewer.
The argument boiled on for years. It still hasn't been settled (AFAIK). The requirement for house traps was strongest on the East coast and may still be.
Anyway, when the trap is outside the building, it usually has 2 cleanout ports, one for each leg of the "U". That's what the OP may have or, as HVAC suggested, maybe it's just a modern 2-way cleanout fitting.
Jim
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The 2 that are close together make what is called a 2 way clean out. The one closest to the house is for cleaning away from the house. The one slightly farther from the house is for going toward the house and cleaning "upstream". The one out 20 feet sounds unusual unless that happens to get you about 50 feet from the back fence. Heavy Rigid cables are 15 feet long. It would take 3 cables to get to the main. The machines can go farther, but it sure is nice to only need one tire full of cable.
Your call on eliminating access to the 2 way. You could move the 2 way out past the patio and probably eliminate the 20 footer.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Keep the whole world singing. . . . DanG

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Good enough answers... I just installed plastic access vaults to each and set the concrete around them...
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