I see where Carla Fong <carla.xspamx.fong@verizon.net> contributed:

Many RV's had no holding tank for grey water.   Since there are very
few places where dumping grey water is both legal and acceptable these
days, the lowest-cost solution is to take along one of the portable
waste tanks.

Will Sill
The Curmudgeon of Sill Hill

Our 84 Toyota Dolphin has only one tank, but the gray dumps into it as well
as the black.  It was really no problem.  Our new Sunseeker has three tanks.
. .

Dan

For an old rig with no gray water tank, the simplest solution is
probably to re-plumb it so the gray water dumps into the black water
tank. The next best solution is to use a blue boy to schlep your gray
water to the dump station, but that means your en route gray water
capacity is the volume of water the drain pipes can hold.

in the olden days not many had grey tanks. the water just drained straight out.
solution, be connected to sewer all the time. or use a portable tank.

mikeyhsd@sport.rr.com

 Hello -

 I'm new to the group and new to RV'ing - sort of getting into it through
 the back door -

 We recently purchased a used 73 Apollo motorhome from our local Goodwill
 store - yes, it's over 30 years old. Yes, I've read the newsgroup and
 figure we bought a wagonload of trouble. At least this thing's troubles
 will be mostly mechanical, not emotional or interpersonal - I can handle
 that. And besides, we spent just $400 on a complete 25' motorhome in
 pretty good shape for its age. I'm told that just the Onan 4Kw 1800 RPM
 generator (with 320 hours on it) is worth more than we paid for the
 whole thing.

 Enough apologizing - now for my question:

 The books from the library say that there are usually two waste tanks -
 one 'black' sewer tank and a 'gray' tank for the less noxious waste from
 the shower, kitchen and bath sink.

 This appears to have only one tank, and a strange plumbing arrangement
 in which the graywater drains do not connect to any sort of holding tank
 but just end at a 'Y" connection immediately prior to the main dump
 valve. There is also a separate gate valve between the black tank and
 the dump valve.

 It appears that there is no holding capacity for graywater. It looks
 like  the gray drains work only when connected to a dump site, unless we
 open the gate valve to the black tank and 'backfeed' graywater into it.
 This seems odd.

 Is there another owner of a similar motorhome out there that can tell me
 how this is supposed to work?

 Thanks in advance -

 Carla
 Under democracy one party always devotes its chief energies to trying to
 prove that the other party is unfit to rule -- and both commonly
 succeed, and are right.  --- H.L. Mencken

I have decided that, in 1973 and earlier, RVers weren't so persnickety about
draining gray water on the ground.  Given that, I believe that some (many?)
RVs were built without a gray water tank.

I am a practitioner of this disgusting (to some) activity - where it's allowed.

When we were tenting and bathing at the campsite behind a homemade "stall"
comprised of clothesline and blankets we did not capture the gray water.  When
we washed our dishes, we did not capture our gray water.  When we brushed our
teeth at the picnic table, we did not capture the gray water.  That was
acceptable.  Somehow, if the same gray water is generated from within an RV,
the gray water becomes radioactive and a threat to the environment, not to
mention the sensibilities of some others.  I don't buy it.

Draining gray water on the ground is legal in MANY places.  While camped in an
electric (only) site for a WEEK, I drained our full-timing gray water from the
end of a 20-ft hose into the grass nearby.  At the end of the week, there was
an area of "stuff" (probably cooking grease) no larger than a Frisbee.  It
didn't attract flies, varmints, the park ranger or space aliens.  It didn't
glow in the dark or even make a "mushy" spot.

Draining gray water on the ground is NOT allowed in, for example, federal
campgrounds.  Given the heavy usage of such facilities, I understand
completely.  Likewise, every private campground I have patronized forbade the
practice.  Given the heavy usage - and HIGH DENSITY (closely-spaced) sites -
combined with the full-hookups available, the ban is understandable.

As Will said, the practice of draining gray water on the ground is against the
rules in some places, particularly heavily-used campsites.  Just ask the park
superintendent if it's allowed.

If it is NOT allowed, you may wish to purchase a tank especially designed to
capture gray and black water.  They are worth EVERY penny that they cost.  I
have a two-wheeled, 30-gallon model.  Of course, I don't use it very often.

<http://www.barkermfg.com/product_pages/tote_alongs.html>