Private water treatment - space needed?

[Rendall]

Hi All -

 

We'll be using a private spring water supply, and will need a filtration and UV kit to be installed on the supply. What type of indicative space is needed for this? We have an old outside stone toilet approx. 1.5m by 1m in the right place so would ideally like to repurpose this by fitting it in there, along the pump, from where the water will then go ten meters or so into the back of the main house.

[Jeremy Harris]

22 minutes ago, Rendall said:

Hi All -

 

We'll be using a private spring water supply, and will need a filtration and UV kit to be installed on the supply. What type of indicative space is needed for this? We have an old outside stone toilet approx. 1.5m by 1m in the right place so would ideally like to repurpose this by fitting it in there, along the pump, from where the water will then go ten meters or so into the back of the main house.

 

Depends almost entirely on the quality of the water coming in.  The first thing to do is get a water sample analysed, as that will tell you pretty much all you need to know.

 

For example, these are the test results for our borehole water, with the maximum allowable values listed:

 

 

From this analysis one thing stands out, the level of ferrous iron dissolved in the water is unacceptably high, at 0.48 ppm, versus an acceptable upper limit of 0.2ppm.  This dictated that we had to fit a filtration system that would oxidise the ferrous iron to ferric iron, and filter out the precipitate.  In turn, this filtration/treatment system needed a minimum back flush flow rate (for cleaning out the sand/Aquamandix filter bed) of about 35 l/m.  35 l/m was too high to be met from just a pump, so that meant installing two, parallel connected, 300 litre pressure tanks/accumulators to provide the initial high flow needed.  These two tanks set the amount of space needed, as they are around 650mm in diameter each and stand about 1500mm high.

 

The analysis could show anything, really, and if it's like our water, may have a significant impact on how much space you need for the filtration etc.  As a bare minimum you will need space for a pressure tank/accumulator, plus a jumbo 10" filter housing (fitted with a 5µ filter) and a UV disinfection unit.  The size of pressure vessel/accumulator, if not determined by things like filtration media backwash rates, will be set by how often you want the pump to switch on or off.  Pumps have a recommended number of on/off cycles per day, and the more often they are turned on and off the quicker they will fail, as they only really wear during the first second or so after being turned on, before water pressure has "floated" the impellers off the internal thrust bearing.  The minimum size of pressure vessel is probably about 100 litres, which will store about 40 litres of water under pressure, meaning the pump will turn on after ~40 litres have been drawn off to refill the vessel.  We store about 250 litres of water in our pressure vessels, and that means we can take a couple of showers before the pump kicks in, but this is probably overkill for most houses.

 

As our water is fairly hard, we also opted to fit a water softener, although whether that's located in the water treatment plant room or the house is really a matter of choice.  I fitted ours inside the house, just to make access more comfortable in winter.

 

 

[Cpd]

Or you could be really lucky like me and get near perfect spring water gushing out of the ground at 10000 litres every 24hrs and amazingly up on top of a hill so gravity fed ! 
my set up is very simple and could have been made even more compact if I wanted.

 

[Rendall]

Thanks Jeremy. We've had the water tested - no big problems. Highest anomaly is manganese, but within limits.

[Rendall]

@Cpd - very compact!