Ha!  The featured pic above of the “poop key” is the key Bill uses to open the dog poop bag dispenser – I thought it an appropriate pic to use for this post!  

Possibly stating the obvious, this chore is called the great equalizer because every single RV, be it a $20,000 travel trailer, $75,000 Class C, $120,000 5th Wheel or $500,000 Class A bus – we ALL have grey and black tanks and they all need to be emptied.  

I’ll start by telling you this, in case there are any newbies out here that haven’t heard it before:  You should always leave your tank valves closed until they are full. (at least 2/3 full anyway)  I’ve told people this and I’ve been met with many confused faces.  Here’s the reason in one word – velocity.  This is especially important in your black tank.  Think about it – I know – it’s a dirty nasty thing – but seriously.  If you were to leave your black tank valve open all the time, you are begging for a pyramid of poo.  Linda (of RV-Dreams) calls it the pyramid of doom – and it would be exactly that – doom!  If the liquid was always emptying out – and the solids weren’t – well – I think you get the idea, right?  If your grey tanks are always left open you can get a build up of soap scum and food particles that can accumulate and possibly get caught in your valve seat causing it to leak and not hold back the tank water. There is also the possibility of getting sewer flies in your grey tanks if you always leave your valve(s) open. On the other hand we know of more than one person who has overflowed their grey tank when using their on board washing machine.  

Related to this is the forever complained about non-working monitor lights in your control panel.  So – assuming they don’t work (trust me – they don’t!) how do you know when it’s time to dump?   I know – sounds like a potentially stupid question – but how do you know?  On your grey tank (some of us have 2 – one for kitchen and one for bath) you may find out by having water not go down – that’s the sure fire, always accurate way to tell.  That’s almost too easy – but can be inconvenient too.  Imagine this – you are washing a sink and counter full of dishes and dirty wash water won’t go down.  UGH!  But – now further imagine that it is pouring down rain – double UGH!  How do we avoid that when the lights in our control box don’t work?  

When we attended the RV-Dreams rally back in spring 2014, Linda and Howard said (during one of the seminars) “you will get to know your tanks” and I – for one – thought “WHAT?”  Three years later I’m here to tell you for myself – you WILL get to know your tanks.  Briefly, here’s how that happened: we timed it – many times.  We would count how many days in between dumping the tanks – after water wouldn’t go down.  We did it with regular use and then again when we were on boondocking use.  Considering we have 2-45 gallon grey tanks and a 45 gallon blank tank – here’s what we’ve learned: we can go 5 days on grey tanks on regular use and about double that, 10 days, on boondocking use.  These are grey tank limits only.  Strictly for black tank – we can easily go 2 weeks.  

Regular use?  Boondocking use?  What’s the difference?  I know you are asking!  Regular use is exactly how it sounds – no conserving – taking regular showers, washing dishes as I usually do.  (Having said that we are not 10 minute shower takers, nor do I leave water just running while I wash dishes)  When boondocking, we take “navy” showers – get in, water on for getting wet then shut off, shampoo, water on to rinse, add conditioner and soap up, water on to rinse.  I know – doesn’t sound like fun – but it works and allows us to stay out longer – fresh tank and bathroom grey lasts longer.  In the kitchen – we will use paper products more so most washing is pots/pans, silverwear and our coffee mugs.  We will also buy bottled water for drinking.  

So, for the black tank – how do you know when it’s full?  Again, quoting Linda of RV-Dreams – it will “sound” different when approaching full.  We have never actually had the black water not go down – but based on sound, we knew it was getting full.  Think about filling a bottle at the kitchen sink, the sound changes as it fills -same principal applies here. Some tanks have a straight pipe down and you can actually hold the flap open and shine a flashlight down and see (I know – nasty right?) but our pipe is curved, so we go on sound.  Two weeks is our number.  We may have been able to push it another day or two, but we felt that was long enough. 

Using these timelines – we are pretty spot on for dumping our tanks.  

With all this in mind, when we are on full hookups, Bill usually dumps every 5 or 6 days, or sooner if needed.  No point in only dumping grey tanks, may as well do them all at the same time.  And, yes, there is a method we follow each time.  

After dumping the bathroom tank, Bill likes to add about 3 minutes (roughly how long it takes to drain both grey tanks) of water to the black tank, enough to have an inch or so of water on the bottom of the tank, which he believes, helps prevent “stuff” from starting to build up on the bottom.  We don’t add this extra water if we will be biombicking.  We also sometimes then add the GEO method to our tank – see below.  

A few notes: 

Some people use a sort of “tank treatment” (there are literally hundreds of options) in their black tank.  While I understand the desire to do this, we never used a purchased tank treatment. You aren’t carrying around a septic system, where enzymes are going to help break down what’s in your tank.  What’s in your tank isn’t going to be in there long enough for them to work (even if we were going to be away from the rig – we wouldn’t leave tanks with anything in them – we would empty before leaving)  Other types are just to mask odors.  I think if you are having an odor issue, you may have a vent issue.  We have had odor issues, and Bill replaced both undersink vents. You can buy them at Lowes or HD.  Also, you should not flush your toilet while your bathroom fan is on (unless you have plenty of other windows open) as you may suck air from your black tank via your roof vent. 

What we (ok – Bill) has discovered is our valve for the black tank sticks (hard to open and close), the other 2 do not – so he’s decided to try using the GEO method for the black tank, which is putting 1 cup each of Calgon and Dawn into the black tank after dumping.  Some people claim it keeps the sensors working, but I’ve heard just as many say it doesn’t help that at all.   It does seem to keep the valves well lubricated, so it’s doing what we want it to do.  

We have found that using plenty of water, using quickly dissolving toilet paper (we use the purple package Scotts) and thorough rinsing works well for us.  If you’re not sure your TP dissolves well try this test. Take one sheet of TP and place in a clear jar (empty Peanut Butter jar or similar) and fill half way with water and shake well for a few seconds.  The TP should break up into tiny pieces. 

Some of you may have only one grey tank, so one less valve to pull.  I believe all have separate black and grey though.  

There you have it!  The least glamorous side of RVing.  If anyone has any different methods that work well for them, please feel free to comment below.  If there are any questions, please feel free to ask.  As I stated at the beginning of this post – we ALL have this chore to deal with – let’s help each other with advice and/or suggestions and/or by answering questions if we can!  

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