SHURFLO Smart Sensor pump matches running speed to water volume required (Pic: SHURFLO)

This, and several more Tech Notes, attempts to answer the most common queries that The Wanderer and I receive from CMCA members. As so many are similar, that the Tech Notes are in digital form on the CMCA website enables the answers to be found in the appropriate article.

Q: How much water does the average person need to drink each day?

A: Doctors recommend at least two litres a day in temperate conditions, two to four in warm conditions and four to six on our increasingly hot occasional days. With the possible exception of a little gin and a lot of tonic water, alcohol cannot be included, but tea, coffee and soft drinks are acceptable. Water, however, is best.

Q: How much water should my RV carry per person/day for general use?

A: The above apart, the absolute minimum is five litres per person/day. This is just enough for cooking, minimised washing-up and cleaning oneself with a wet flannel, and a tad left over for cleaning teeth. Fifteen litres allows for a soaping and a few seconds shower, but 20 litres is preferable. If travelling in the outback add another five litres (per person/day) – and 10 litres for the 1000 km Tanami, and the 1400 km Canning Stock Route.

Q: What size tanks are typically included in a production campervan or motorhome?

A: Some small campervans hold (a less than adequate) 50 litres, but some 80 or so. Motorhomes carry from 80-300 litres. If feasible it is best to have separate tanks.

Q: What type of tank do you recommend?

A: Health-wise I prefer stainless steel but such tanks must be well braced or they  may suffer stress-related cracking. Many now use polythene. If you intend to travel on dirt roads the tanks need protecting against damage from rocks (in effect) thrown back at them with some force.

Q: My water tank takes ages to fill and keeps on ‘belching up’ the filling water. I’ve fitted larger hose from the filler to the tank but if anything it made it worse? How can I fix it?

A: This is far from uncommon with production RVs – it amazes me that not all tank makers address this issue. As water is poured or pumped in it compresses the air in the tank. Once that pressure exceeds that of the incoming water it burps or farts its way out, usually with a burst of water. The tank must have a separate outlet and hose that allows the air to escape. It also needs to allow air in when you pump water out. The hose needs be about 20 mm diameter. The upper end must be well above the tank full level or water will be lost. If feasible, have that hose within an enclosure such that dirt is not drawn into the tank.

Q: How can I be sure the water I need is free of bugs?

A: Short of filling up only in major towns you can’t. It’s better to assume there are bugs. A major risk in caravan parks and elsewhere is that unthinking idiots can and do rinse their toilet waste containers under drinking water taps. Resultant disease-causing faecal giardia and also cryptosporidium is, however, safely handled by adequate filtering. You need a coarse filter before the RV’s pump, a 5-10 micron filter and final one micron paper filter after the pump. That one micron filter will trap those bugs, but must be replaced at least once a year.

Q: How hard is it to obtain good water in the outback?

A: It can be difficult, particularly in inland South Australia and up north. Fuel stations will usually allow you to fill your tanks but usually conditional on your first filling up with fuel. Caravan parks too allow you to fill up if you are staying there. An excellent good alternative (for cooking and drinking water) is the 12-15 litre strong plastic casks of ultra-clean water sold by virtually all fuel stops and mini-supermarkets. My wife and I used to travel extensively in the outback and eventually used these routinely. They are not expensive.

Q: My electric fuel pump is very noisy. It even wakes us up at night as it pumps for a few seconds even though we have not drawn any water. Can I fix this?

A: You probably have two different problems. There are many ways of fixing them, however.

Until recently most RV pumps maintained full working pressure in the system. When water was drawn the pump sensed this and ran flat out to restore that pressure. The problem was that the pump responded to even a tiny pressure drop, so would operate occasionally not only if there was a tiny drip, but as the typically used plastic pipes expanded and contacted with quite minor temperature changes. Noise from the pump itself was also transmitted through the piping. Solutions include fitting a pump with a pressure vessel (known as an ‘accumulator’). Minor water pressure changes are absorbed by air pressure. Another is to fit one of the new generation (but costly) variable speed pumps made by SHURFLO (previously SHURflo) and others. The pressure  vessels mentioned above can neither be used, nor are they needed with these pumps.

Noise transmitted through piping is usefully and cheaply reduced by having the inlet and outlet hose hanging loosely in a loop. These will move around as the pump operates, thus dissipating the otherwise noise-making energy. This is surprisingly effective.

Q: We only use our motorhome once or twice a year but need to replace the water pump every second year or so. Is this normal?

A: Most RV water pumps need to be operated every month or so or various internal valves get stuck. They only need running for a few minutes.

Q: I’m amazed at the high price of filters. And why do they not have standardised holders?

A: There is a de facto standard followed by many filter makers, and these are ones to buy. The one you have is only made that way so that you are locked into buying filters from that maker (usually at  two/three times the others’ prices). Don’t be fooled by ‘quality’ sales talk.

Q: I’m a bit paranoid about water quality so am thinking of using the reverse osmosis system. Any thoughts re this?

A: Yes. It’s massively costly and overkill for RV use. Further, it is only usable where there’s almost unlimited water and electrical power. They produce truly good water but only 10 percent or so of that processed is used (i.e. 90 percent is dumped). You also need a generator to run it. It’s fine for boats as they are surrounded by water anyway – and usually have ample power, but impracticable and unnecessary health-wise for an RV.

The answers in this series can only be short and concise. All such matters are, however, covered in depth in my various books – on all aspects of RVs, solar, etc. Most are stocked and sold by CMCA NHQ – or directly by mail from caravanandmotorhomebooks.com . 

Category: Technology
Written: Fri 01 Jan 2016
Printed: January, 2016
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