Holding tank / Diesel tank

[concentrik]

I don't have a holding tank but I do have a spare 300L s/s diesel tank which I was thinking of using. I only need one fuel tank and rather than cut the other out I was wondering about pressing it into service as a holding tank. It has the usual fuel filler deck fitting - would this work as a pump-out point?

Heads are about 5m from the tank and rather than running a bulky waste hose through the boat I was thinking about a macerator.... any pointers?

 

[Talulah]

I don't have a holding tank but I do have a spare 300L s/s diesel tank which I was thinking of using. I only need one fuel tank and rather than cut the other out I was wondering about pressing it into service as a holding tank. It has the usual fuel filler deck fitting - would this work as a pump-out point?

Heads are about 5m from the tank and rather than running a bulky waste hose through the boat I was thinking about a macerator.... any pointers?

The fuel filler won't work as a pump out. The pump out has to reach down to the bottom of the tank. Most fillers stop at the top of the tank.
Macerator ok.
Stainless has a limited life before Urine eats through it.
Urine finally ate through our Stainless HT yet amazingly Stainless HT's are still fitted by some manuafacturers.

 

[RupertW]

The fuel filler won't work as a pump out. The pump out has to reach down to the bottom of the tank. Most fillers stop at the top of the tank.
Macerator ok.
Stainless has a limited life before Urine eats through it.
Urine finally ate through our Stainless HT yet amazingly Stainless HT's are still fitted by some manuafacturers.

Wow - we've got stainless holding tanks 12 years old which were used by charter crews for 6 months solid each year for 8 years. No external signs of problems yet but I guess we'll only know when if a hole appears.

 

[Talulah]

Wow - we've got stainless holding tanks 12 years old which were used by charter crews for 6 months solid each year for 8 years. No external signs of problems yet but I guess we'll only know when if a hole appears.

It eats through from the inside. You know you are now tempting fete and your summer cruise will have that lingering doubt. "Is that the heads smelling or has the tank started leaking?" The doubt will prey on your mind.
In reality it depends upon the design and use.
On some boats fitted with an HT the HT may rarely be used or the contents pass through without stopping. On the Najad 390 however all the toilet waste goes in to the HT and is pumped out. The pump always leaves a small amount in the bottom corner of the tank and this is were they finally go. Our tank lasted maybe 15 years.

 

[pvb]

I don't have a holding tank but I do have a spare 300L s/s diesel tank which I was thinking of using. I only need one fuel tank and rather than cut the other out I was wondering about pressing it into service as a holding tank. It has the usual fuel filler deck fitting - would this work as a pump-out point?

Heads are about 5m from the tank and rather than running a bulky waste hose through the boat I was thinking about a macerator.... any pointers?

Leaving aside the durability of stainless steel holding tanks (mine's 20+ years old but admittedly isn't used much), the people to talk to are Lee Sanitation. They used to have a lot of general information on their website, but most of it has now disappeared. Fortunately, you can still download their article on holding tanks here.

 

[RupertW]

It eats through from the inside. You know you are now tempting fete and your summer cruise will have that lingering doubt. "Is that the heads smelling or has the tank started leaking?" The doubt will prey on your mind.
In reality it depends upon the design and use.
On some boats fitted with an HT the HT may rarely be used or the contents pass through without stopping. On the Najad 390 however all the toilet waste goes in to the HT and is pumped out. The pump always leaves a small amount in the bottom corner of the tank and this is were they finally go. Our tank lasted maybe 15 years.

Ours is a pass through and gets pumped out at sea by opening the seacock and flushing the loo a few times, so hopefully isnt too bad. I will do my best not to worry and will probably succeed as there are plenty more dodgy bits of the boat to worry about instead.

 

[duncan99210]

Visit Tektanks website for info on holding tanks, sewage handling a whole lot more. Although they are makers of plastic tanks much of what their site has is general stuff about toilets and how to handle the waste. Link is here http://www.tek-tanks.com/

I bought all the stuff for fitting our holding tank from them and they were happy to guide me through the process of sorting out what we wanted. No pressure to buy anything beyond what I wanted and all good quality stuff. Usual disclaimers, just a satisfied customer.

 

[affinite]

I don't have a holding tank but I do have a spare 300L s/s diesel tank which I was thinking of using. I only need one fuel tank and rather than cut the other out I was wondering about pressing it into service as a holding tank. It has the usual fuel filler deck fitting - would this work as a pump-out point?

Heads are about 5m from the tank and rather than running a bulky waste hose through the boat I was thinking about a macerator.... any pointers?

Sounds like a good use of the old tank to me but unsure how the Macerator would fit in. Macerator is normaly used to empty the holding tank, not fill it ! Maybee changing the bog for an elec one inc macerator would work and cope with your 5m run.

PS comment about the redundant filler is correct but it could be used as the rinse inlet.

 

[dulcibella]

Corrosion by urine shouldn't be a problem provided the tank is pumped out regularly and then rinsed with several pump-out/pump-in cycles.

 

[Tranona]

The problem with the remote tank is that you always have the 5M pipe full of waste. The original installation on my boat was like that, with the tank the opposite side of the boat. I did not specify that type based on other peoples' experience, but retrofitted a gravity tank.

You can avoid the pipeful by pumping more water through, but that limits the capacity of your tank (although a 300l tank is 4 or 5 times bigger than most). Using an old fuel tank may have problems with the positioning of baffles and where you place the inlet, outlet and pumpout stack. A macerator is usually used to pump overboard - you will need a pump anyway. The advantage of the macerator is that it uses a smaller bore outlet than a normal 38mm seacock. Although SS is not now the material of choice for holding tanks, it does make sense to try and use your old tank if you can. With that capacity you could also use it for grey water.

 

[Twister_Ken]

300 litres seems big, bigger than your average.

If it means it is emptied less often, you have quite a good methane generating plant there. You might want to make sure it's got a good vent (or plumb it in to your cooker!).