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Old 11-23-2015, 12:49 PM   #1
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Austin , Texas
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Gray water versus Holding.... Whaaaat?

So, I'm building a trailer from scratch and about to install a gray water tank. I'm not replacing anything so there are no original requirements.

But I am confused. I see square tanks all over the inter webs that say, "Holding or Gray water" and they have 3 weenie small blue taps and on low pressure red one. I see Slanted tanks with a BIG output at the low end also.

I would guess for gray water you would want some BIG input and BIG output.

I am not going to have a shower or bathroom, it's just for a kitchen sink. But still, could be some solids in that.

So what am I looking for? The slanted tanks or the cheaper square ones ... but then I'm guessing I would have to tap in two big inlet/outlets?

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Old 11-23-2015, 06:10 PM   #2
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Gray water versus Holding.... Whaaaat?

Typically the DWV (drain,waste, vent) system for a sink are 1 1/4" to 1 1/2". Most inlets/outlets on Grey water tanks are 1 1/2" to 2".
Sloped bottom tanks may flush more efficiently but only if the outlet is large. One must keep in mind the size of the vent as well. It must be large enough for free air flow into the tank as the waste is discharged. Otherwise you may get gurgling. Fill a plastic jug with water. Turn it upside down and it will gurgle. Turn it at an angle it will flow steady.

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Old 11-23-2015, 06:51 PM   #3
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2014 25' FB Flying Cloud
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Read about an Austalian trailer that the manufacturer makes to use in the outback that uses the grey water tank to supply water to the toilet for flushing. Interesting concept, especially if you could pick the grey water tank or the fresh water tank as your source of flush water. Seems a Y pipe fitting with a bilge pump might do it. Anyway, something to think about
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Old 11-23-2015, 09:31 PM   #4
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Thanks. I found a slanted one just right.
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