Grey-water level gauge

Water level gauge was showing wrong level ie showed full when tank was empty. I rinsed out the tank a couple of times with fresh water and drained. Then added a handful of ‘Washing Soda Crystals’ with some warm water and went for a drive to give it a good slosh about and hopefully remove accumulated crud from the sensors. Gauge now gives a roughly correct indication of water level in the tank.
Feeling pleased.

I have never needed to do that. Does it depend on what has been put down the drain?

Didn't even know there was a grey tank level gauge!! I think mine has a light which comes on when its full, as it never is, I have no idea if it works!!

Petermcd.     I have similar issue with waste water level indication and have tried adding various solutions,including driving home from site with dishwasher tablets in tank.None have done the trick so far so will give soda chrystals a try.Tomorrows job!
Thanks for providing me with another thing to try.

Kdc, I’m always interested in these type of threads. Not because I have any issues at present but it’s always good to know about potential problems that may crop up in the future.
I’m surprised that you have trouble with the waste water indicator in a 2019 van. I live in a hard water area and generally fill the fresh tank at home but have not yet experienced the expected problems with the mentioned waste tank after nearly 2 years.

Could you possibly have a different fault rather than a dodgy sensor caused by the water? Just a thought.

Dbvwt....I also fill fresh water tank from home but don’t think that means much when refilling whilst out,also don’t yet think problem is limescale as fresh tank readings are ok.
Yes tank is still young.....my readings are inconsistent  usually telling me there is some content when I know it’s empty. I will raise the problem with dealer if I cannot find quick fix,Hopeing it may just be build up of Gunge in waste tank which is why I am prepared to try soda chrystals to see if it clears the problem,If it does it’s good trial for future use. There may well be a more technical fault as you suggest but that will become the dealers task if this don’t work.

Hope you get it sorted, let us know the outcome, all info is good info 

Kdc wrote:Dbvwt....I also fill fresh water tank from home but don’t think that means much when refilling whilst out,also don’t yet think problem is limescale as fresh tank readings are ok.

 Likewise, my fresh water tank's gauge is fine (and that's the important one) but my waste tank's gauge has stopped working. Not unduly fussed, because I can guesstimate contents of grey contents from that of the fresh tank. 

Shall nevertheless try the sodium carbonate solution.

Cymro

I cleaned both my tanks out in Spring with some Elsan tank cleaner and it started reading dodgy afterwards.

I did noticed around the filler cap where it had dripped it had dried to form a powdery residue, so wouldn't be surprised if it's dried on the probes like that, as although I rinsed the tanks afterwards, it was left a while without use over lockdown so maybe a possibility.

Hoping it'll wash off with repeated use.  I think it's common over time though.  Scale remover would be my first check on an older van but interesting that soda crystals worked.

That’s interesting greyhound.........I cleaned my waste tank after lockdown with Elsan cleaner and have started these inconsistent readings since, if it is a contributing factor then hopefully the soda may sort it.Will know after tomorrow’s task.

Perhaps doing nothing at all is the answer 

Joking aside it’s a bit strange that in some cases treating the tank has maybe caused problems?

Like many of you, my fresh water gauge reads (more or less) correctly but the grey water one was ‘iffy’. I believe the best solution would be to properly clean the metal sensors in the tank but as there is no access hatch and to fit one would involve lowering the tank and cutting one, the soda crystal route seemed to be worth a try. Worked for me and can’t cause any harm ..... can it ?

I’m sure it can’t Peter, I will put some in before the end of season to hopefully prevent trouble in the future.

The sensors are mounted in rubber bungs along the side that you can possibly pull out to clean.

I know this as one of my fresh tank sensors started leaking and when I drained the tank it practically fell out when I moved it.

I have 'glued' it back on place with a thin bead of sikaflex which will definitely hold it, but thin enough it could be removed if needed.

Not sure if all the sensors can be reached but the bottom 2 of the fresh tank are easy on the Symbol. I wonder if a thin hand wriggling up along the side of the tank could get them out?

how difficult is it in 2020 to fit a system that accurately measures the content level of a water tank? too darned difficult, perhaps.
this seems like another AS 'weve always done it like that' system despite the world and his wife reporting that it isnt fit for purpose.
why should owners have to f*rt about with umpteen different 'cleaning solutions', driving round the country to try and sort it out.
even a Thetford toilet cassette full of 'cr*p' (hard or soft water) still manages to convey a 'full' indication to the toilet contol panel by the most primitive float valve....
on a £60+k PVC one would expect water tank levels to be accurately indicated without the measures so regularly posted here....wouldnt one?
i certainly would.

My 2019 WXL have been replaced with float sensors under warranty.

Ours has been showing half full (it had new sensors a couple of years ago) and on site the valve is left open draining into a waste aster.   I decided it was yet another Sargent Fault and ignored but after emptying the wastemaster today it correctly showed empty.  Another Sargent Dry Joint!!

We buy two large bottles of cheap Aldi coke, empty tank, close drain. Pour bottles down sink, by time you get to site coke sloshing around in tank will clean off sensors. Do this twice a year, no problems since.

Mel C wrote:We buy two large bottles of cheap Aldi coke, empty tank, close drain. Pour bottles down sink, by time you get to site coke sloshing around in tank will clean off sensors. Do this twice a year, no problems since.

Sorry to revisit this post, but I too have this problem and was searching for solutions on the forum. I've come across this Coke idea before, and wondered what was in Coke that made this work. Apart from the usual flavours and sweeteners, the ingredient phosphoric acid stood out on the list. For my industrial experience, one of the uses of this ingredient is a cleaning / passivating agent for the food industry.

Looking at the solutions proposed we have a number of agents that appear to be effective at cleaning the tank level sensors:

--- Citric Acid
--- Soda crystals (which are sodium carbonate - the anhydrous sodium salt of carbonic acid)
--- Cola - containing phosphoric acid
--- Vinegar - which is a solution of acetic acid

Anyone spot a pattern? Yes, they are all mild acids!

The question then becomes, what concentration is needed? Well 'Coke' contains about 17mg phosphoric acid per 100ml according to Google, but some cheaper Colas might be as high as 50mg / 100ml. Assuming a 100 litre tank, this equated to 50g of phosphoric acid for the tank. I've searched on Amazon and you can get 5 litres of 45% phosphoric acid for £20, so I think just over 100ml of this will provide the 50g needed. 

Vinegar is typically 5% acetic acid, so if we use equivalent numbers, you'd need 10 litres to get to the same level of dilution (50g) in a full tank.

The numbers are an illustration of course, based on a full tank. If we assume '2 bottles of coke' which I assume is 4 litres total, and use the 'drive to slosh method', you'd need 4-5 ml of the 45% phosphoric acid solution or half a litre of vinegar.

The advantage of phosphoric acid (and coke) and vinegar is that they are in solution, and no dilution is required. 

For waste tanks there is also the question of degreasing, which I've not covered yet. I tried the dishwasher tablet 'drive and slosh method' this weekend but it hasn't solved the problem. Perhaps a 2-step approach is needed for waste tanks - detergent then acid - so I'll be trying some acid next.

Hope this is useful.......

petermcd wrote:Water level gauge was showing wrong level ie showed full when tank was empty. I rinsed out the tank a couple of times with fresh water and drained. Then added a handful of ‘Washing Soda Crystals’ with some warm water and went for a drive to give it a good slosh about and hopefully remove accumulated crud from the sensors. Gauge now gives a roughly correct indication of water level in the tank.
Feeling pleased.

Have you driven on wet roads just before this happened?

We have always wondered why the waste full light has never illuminated on our control panel, but never worried about it unduly.   Last week o/h had to remove the tank to fix a major leak on the outlet pipe* and found there is neither a wiring connection to it, nor any sensor on the waste tank, so conundrum solved - they didn't bother with it !

* A/S didn't use the pre formed outlet stub on the waste tank on our 5.4m van as it obviously too close to the leaf spring. So they fill it with Sikaflex and fit a threaded connection themselves higher up on the forward facing side safely away from the spring. Surprising that it has taken 9 years to unscrew & leak.

What isn't surprising now we've realised it, is why the waste tank often smells. There is always water that cannot drain out as the outlet is fitted too high.

Ours started giving misinformation after driving on wet roads so here is what I found and the cure. It’s been good ever since.

The problem is simple but the solution is a little more complex. If your handy at joining electric wires it’s easy.
1st, the problem. Both of your tanks have 4 or 5 wires connected to little fittings in the side of the tank. These are all colour coded and they go from the tank back up through the floor to the Sargent controller. The issue is the fact that there is a connector between the tank and the underside of the floor. The connectors are not fit for purpose as they are only simple 6 way plastic plugs & sockets designed for internal use not external. AS fit these and just wrap a bit of tape around them. As you drive in the wet, water gets in them and short circuits the cables giving false readings.
The solution is to cut them out and rejoin the wires. Be careful not to mismatch the wires as that would give false readings too. I did mine by soldering the wires together and covering them with heat shrink. This makes a good waterproof joint (I hope). Only time will tell but so far so good.

Sound suggestion Womble - thanks. 

Are you talking about the grey waste tank though, or the fresh water?

As far as I know, the grey tank has only one sensor to tell you when it's full.

Gromit wrote:Sound suggestion Womble - thanks. 

Are you talking about the grey waste tank though, or the fresh water?

As far as I know, the grey tank has only one sensor to tell you when it's full.

Both. Both my tanks have 4 level points.

Interesting.

I'm sure our grey tank has only the one.

I think??