Tuesday, 6 September 2011

Managing the Potable Water

Potable water is one of the three essential bulk storage requirements when living on a boat.  The others being diesel and sewage.  Whilst we are on the mooring ready access to water isn’t an issue.  However it will be a major consideration when we start constantly cruising. 

Kelly-Louise has a good size fresh (potable) water tank which is located under the foredeck and I wanted to establish how long the storage capacity would last before the tank went from full to empty.  The answer is 3 days!  Obviously we’ve just moved on board and have yet to adapt our habits towards water conservation.

We are not going to be able to increase the size of the water tank on Waiouru so we need to start changing our water usage habits.  My assumption is access to water won’t be an issue during summer but we do need to consider a water minimisation strategy during those periods when moving the boat will be difficult or impossible.

A water usage audit is required.  This will enable us to identify where excess water is used and what opportunities exist to internally recycle water.

One of the advantages of reaching the beginning of your “Golden Years” is you have a lifetime of experience to draw upon.  Many years ago as a young soldier I spent time in the jungle of Malaya and the Australian bush.  The former was very humid resulting in a large intake of water due to perspiration.  The latter was very dry with limited access to water.  I’d regularly carry between 6-8 litres of water and consume most of that in a day.  When you have to carry your water around all day you learn to conserve it.  The water would be used for drinking, cooking, cleaning and washing.  My strategy was to ensure I was hydrated during the day by drinking from the water bottles as required.  Each morning I’d boil a half-pint mug of water and make tea.  I’d drink half the mug and then dip a corner of my neck sweat-rag in the tea and wipe each eye clean.  Next I’d use a small amount of the tea to clean my teeth.  Finally, I’d use the remainder of the tea to shave (remembering to use the sweat rag to clean the inside of the mug otherwise the next drink of tea would be “soapy & gritty”) Smile  Somehow I don’t think I’ll be able to convince Jan to adopt the above practices!

Where is our fresh (potable) water going…….

  • Drinking (essential)
  • Cooking (essential)
  • Washing dishes (essential)
  • Personal hygiene (essential)
  • Shower (not essential)
  • Toilet flush (not essential)
  • Laundry (not essential)
  • Other uses (not essential)

The first two can’t be used for recycling as they are consumed.  The dishes, shower and personal hygiene water might be able to be used to flush the toilet.  However I need to identify whether the impurities might adversely affect the bacterial process in the tank.  Moreover it is probably just as easy to take water from the canal to flush the toilet.

It appear the ability to recycle our potable water is limited.  Therefore we need to consider water minimisation.  Perhaps we can carry more crockery and reduce the washing frequency.  Maybe we can wash the dishes only once per day. 

I suspect we run the tap in the bathroom too much.  We should probably develop a habit of adding a set minimal amount of water to the hand basin and disciplining ourselves to managing within that amount for washing, teeth, etc.

As the weather gets cooler and we cruise less we can probably reduce the frequency of showering.  After that we can revert to an old trick of turning on the shower to get wet.  Then turn it off and wash with soap and flannel.  Finally turn it back on and rinse off.  If access to water is really difficult then we can flannel bath in the shower.

I could grow a beard and eliminate the requirement for shaving water, or purchase an electric razor.

Now I ask myself, “Why the focus on water rather than diesel or sewage?”  And the answer is… because we are consuming the storage capacity of the water faster than the other two!  I wonder if it is possible to purchase a simple water purification system that would enable us to produce potable water from the canal?


Peter and Margaret said...

There are two possible issues related to using water from an outside source in the Tecma. The first, is that the flush consists of multiple parts. Even the simple number 1 flush, draws water in, exits the waste, closes the exit trap whilst still drawing a little more fresh water, then shuts down. A gap of about 30 seconds elapses before it operates one final time to flush through this final, small amount of water. I believe this is to clean any debris left on the exit traps and impellers. This would be difficult to emulate by adding foreign water to an otherwise dry flush. Secondly, as you have already found out, the Tecma is very sensitive to foreign bodies going down it, even the allowed type of tissue, so any external water that may be used, must not contain any debris, even of the minutest size, which in practical terms means filtering any water you want to use for the purpose. I believe that water conservation would be better focused on other, less sensitive areas.

nb piston broke said...

Hi Tom My fresh water tank holds 250gals you dont say the capacity of the one on KL or your boat if it only lasts for 3 days is it to small or are you being wastfull ours lasts us 10-14 days on average however you will notice the diference if you have visitors who brush their teeth with the TAP running Paul

Tom and Jan said...

KL's tank capacity is 346 litres or 76 gallons. So it's less than one third the size of yours.
That said; we do need to focus on reducing the amount of water we use.

Bruce in Sanity said...


That is a very small tank. We have 780 litres on SA, which is on the larger end; like Piston Broke, we reckon to go around 10 to 14 days on a tank, though often refill well before that; on a slow tap, it can be a lo..ong wait!

Sheila has just added a bit on water conservation to her page on my blog.

All the best


Tom and Jan said...

I've now read Shelia's water conservation hints. Some very valuable points to remember. I also need to check with our builder and confirm the capacity of the water tank.

Anonymous said...

For what it's worth, I've spent over 20 days away in my caravan this year, and my water consumption is generally about two and a half gallons per day.

This includes one shower, washing up, teeth cleaning, and water for porta potti. Also water for coffee, and hand washing as necessary.

I think flush type toilets as used on many boats are far more water hungry.