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Design Your Own RV or Caravan Plumbing System

Article by Peter Smith - Caravans Plus

We get many requests on how to setup the plumbing with different levels of complexity from a manual pump in a campertrailer to a full system feeding a Hot Water System with multiple outlets and using multiple tanks and mains pressure when available.

It is suggested to read from the start as many hints are not repeated in the more complex systems.

1. Portable tank with tap

Caravan Jerry Can

The most basic of water tanks is a portable tank with a tap. It is simple, reliable, and has the advantage that you can take it to a refill point.

The disadvantage is the tap can get damaged and they can be heavy to carry and lift into position. You need to release the lid to allow air in as the water is used.

Great for tents and Camper Trailers. We recommend the plastic style that does not allow light in to keep your water fresher.

PVC Fresh Water Jerry Can - 22 Litre With Threaded Outlet

PVC Fresh Water Jerry Can - 22 Litre With Threaded Outlet

3 In Stock Now.
$38.95
$32.95
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Water Tank Drain Tap, Twist, 3/4 Inch BSP Thread

Water Tank Drain Tap, Twist, 3/4 Inch BSP Thread

4 In Stock Now.
$3.55
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2. Manual pump and remote water filler

Caravan Plumbing

In the above diagram, following the flow of water:

1) Water Inlets/Filler (see full range and prices ) - In this case a lockable water filler is shown. It is secured to the outside wall and has a filler hose connected with hose clamp. Some fillers incorporate a breather outlet for a smaller breather hose. In this case it is not shown, as a number of tanks only have a drilled hole for a breather so cannot be connected. The breather hose also prevents any dust getting back into the tank. The water filler must be positioned above the top of the tank. One popular inlet is also shown below.

Lockable Water Filler - 25mm OutletSpecial Price

Lockable Water Filler - 25mm Outlet

20 In Stock Now.
$32.95
$25.95
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2) Filler Hose - These are usually 25mm hose and must be food grade. This hose is connected with hose clamps at both ends. It is best laid as a continuous slope to the tank to help prevent air locks while filling. Below is our recommended hose for this purpose.

PVC Black Hose, Food Grade, 25mm ID (3.5mm Wall), Per Metre

PVC Black Hose, Food Grade, 25mm ID (3.5mm Wall), Per Metre

25 In Stock Now.
$6.85
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3) Water Tank (see full range and prices ) - All our water tanks are suitable for drinking water and come in many shapes, sizes, strengths, and outlet combinations. When located underneath the body it is best to provide a stone shield unless a Heavy Duty tank is installed which can withstand most normal dirt roads.

Recently the range of tanks sizes available has been reduced in favour of the modular tank system. The practical design of the new tanks enable a huge range of water storage solutions for any installation. Our top selling standard tank is also detailed below with matching brackets. You will also need a threaded connection as detailed on the tank.

Modular Caravan & RV Fresh Water Tank - 43 Litre - 860 x 260 x 220mm

Modular Caravan & RV Fresh Water Tank - 43 Litre - 860 x 260 x 220mm

10 In Stock Now.
$63.96
$51.95
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Ampac Plastic Fresh Water Tank - 59 Litre - 840 x 480 x 180mm

Ampac Plastic Fresh Water Tank - 59 Litre - 840 x 480 x 180mm

6 In Stock Now.
$90.00
$59.95
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Galvanized Brackets To Mount Tank - Suit 59 & 82 Litre AMPAC Tank. Pair

Galvanized Brackets To Mount Tank - Suit 59 & 82 Litre AMPAC Tank. Pair

12 In Stock Now.
$55.95
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4) Outlet Hose - These are usually 12.5mm hose and must be food grade. When used with a manual pump as shown a hose clamp is used on both ends. We recommend the black food grade hose so that any water that stands in the hose for extended periods will not allow algae to form. Take care not to install the hose where kinks can prevent water flow.

PVC Black Hose, Food Grade, 1/2 Inch ID(2mm Wall), Per Metre

PVC Black Hose, Food Grade, 1/2 Inch ID(2mm Wall), Per Metre

57 In Stock Now.
$2.95
$2.15
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5) Hand/Foot Pump (see full range and prices ) - These are easy to use and will suck the water up from the tank. They should hold water in the feeder pipe between uses. Pumps that allow the water to drain may need to be replaced or seals replaced or a non-return valve added below the pump. A couple are shown below.

Hand pump, BREHA, BLACK

Hand pump, BREHA, BLACK

7 In Stock Now.
$41.95
$32.95
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Camec Chrome Metal Hand PumpBest Seller

Camec Chrome Metal Hand Pump

19 In Stock Now.
$46.95
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6) Sinks (see full range and prices ) - There are a multitude of sizes, with or without dish drainers, to suit most situations. They come in stainless steel or acrylic. Our most popular sink which includes the waste fitting and drainer is shown below.

Stainless Steel Sink/Drainer, 590mm x 370mm, SMEV

Stainless Steel Sink/Drainer, 590mm x 370mm, SMEV

8 In Stock Now.
$161.00
$91.95
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7) Drainage Hose - These can be any style of hose but we recommend the corrugated sullage hose. The corrugations prevent kinking. Ensure the hose is self draining or any undrained water that gets trapped will smell. The below hose can be cut for the sink with the balance used to run the grey water into sullage drain. A joiner is also shown.

25mm Corrugated Sullage Hose, 10m Roll

25mm Corrugated Sullage Hose, 10m Roll

10 In Stock Now.
$35.95
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PVC Joiner 25mm Barb

PVC Joiner 25mm Barb

10 In Stock Now.
$2.95
$2.35
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The above plumbing system is fairly standard in small caravans and camper trailers.

3. Electric pump, filter, and accumulator

Caravan Pumps, Filters, Accumulators

In the above diagram, following the flow of water:

1) Water Inlets/Filler - In this case a lockable water filler is shown. It is secured to the outside wall and has a filler hose connected with hose clamp. The breather hose (11) connects to the top of the tank. Breather hose and clamps shown below.

PVC Clear Breather Hose, Food Grade, (3/8 inch) 10mm ID, Per Metre

PVC Clear Breather Hose, Food Grade, (3/8 inch) 10mm ID, Per Metre

46 In Stock Now.
$2.95
$2.45
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Hose Clamp 10-16mm

Hose Clamp 10-16mm

208 In Stock Now.
$2.25
$1.45
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2) Filler Hose - These are usually 25mm hose and must be food grade. This hose is connected with hose clamps at both ends. It is best layed as a continuous slope to the tank to help prevent air locks while filling. Suitable clamps shown here.

PVC Black Hose, Food Grade, 25mm ID (3.5mm Wall), Per Metre

PVC Black Hose, Food Grade, 25mm ID (3.5mm Wall), Per Metre

25 In Stock Now.
$6.85
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Hose Clamp 25-40mm Zinc Finish

Hose Clamp 25-40mm Zinc Finish

45 In Stock Now.
$3.25
$2.15
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3) Water Tank - All our water tanks are suitable for drinking water and come in many shapes, sizes, strengths, and outlet combinations. A heavy duty 75 litre tank is shown, together with an outlet that will match the black 1/2 inch hose.

Enmach Heavy Duty Poly Fresh Water Tank - 60 Litre - 810 x 615 x 200mm

Enmach Heavy Duty Poly Fresh Water Tank - 60 Litre - 810 x 615 x 200mm

4 In Stock Now.
$254.95
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Water, Director 3/4 Inch BSP To 1/2 Inch Or 13mm Barb

Water, Director 3/4 Inch BSP To 1/2 Inch Or 13mm Barb

46 In Stock Now.
$2.60
$1.55
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4) Cold Water Hose (full range and prices) - These are usually 12mm or 1/2 inch hose and must be food grade. When using an electric pump we recommend placing some flexible hose before and after the pump to reduce vibration being transferred to the RV body. This makes them quieter.

5) Filter (full range and prices) - We always recommend the use of a user cleanable filter before the water pump. Warranty will not cover ingress of dirt into a water pump. The one shown below screws directly onto the pump we recommend.

SHURflo 1/2 Inch BSP To 12.5mm Barb, Filter

SHURflo 1/2 Inch BSP To 12.5mm Barb, Filter

109 In Stock Now.
$14.15
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6) Pump (full range and prices) - There are a multitude of sizes and in most cases we would recommend an auto pressure pump that will switch-on when the tap is opened. 10 litres per min is ample for showers. Sinks can use less. It is recommended to incorporate some flexible drinking water hose adjacent to the pump to reduce annoying vibrations. Our most popular 12V pump is shown here, but there are others.

SHURflo 4009 - 12V Fresh Water Auto Pump - 11 LPM / 45 PSI. 1/2in Male BSP **Best SellerSpecial Price

SHURflo 4009 - 12V Fresh Water Auto Pump - 11 LPM / 45 PSI. 1/2in Male BSP **Best Seller

384 In Stock Now.
$180.00
$101.95
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7) Accumulator (full range and prices) - This is optional. They decrease the number of times a pump needs to stop and start when pumping less water than the pump is capable of. Some pumps incorporate methods to reduce this also. These pumps will indicate Smart or Bypass in their description. If you select our recommended pump above it does have bypass that works to a point, but if a very low volume of water is being pumped through a water filter you may still require an accumulator.

8) Cold Water Tap (full range and prices) - Opening the tap will release the pressure in the pipe and cause the auto pumps to start.

9 & 10) As before.

11) Breather - When a tank provides a top hose connection (usually 10mm) this can be directed to the water filler. If the water filler has no breather connection then the breather hose should be positioned to prevent dust ingress. An open breather is essential to prevent damage when filling a tank and a blocked breather can cause poor flow rates by the pump.

The above plumbing system does not incorporate mains pressure or hot water.

4. Adding mains pressure and hot water

Caravan Plumbing Mains Pressure

In the above diagram, following the flow of water:

1) Water Fillers - Two provided here so each tank can be filled independently. They are connected to the tank with 25mm food grade hose.

2) Water Tanks - When more than one is included, they should be at the same level if pumping from both at the same time. Breathers have been left off for clarity only. Some tanks come as Primary & Secondary with a link hose between them - in which case only one filler is required.

3) In Line Taps - These allow either tank to be isolated from the pump and prevents pumping of air if one tank empties. Opening both taps will allow tank levels to equalise provided the connecting pipe does not rise above level and get an air lock in it.

4) Flexible Hose - When using semi rigid pipe in your system you should prevent pump vibration/noise in your pipe work by including about 300mm of loose flexible hose on both sides of the pump.

5) Filter & Pump - You must use a filter to keep your pump warranty and for the above configuration Caravans Plus recommends the Shurflo 4009 for price, reliability and quietness. The Shurflo 4009 does not require an accumulator.

6) Non-return Valves - These are essential when combining mains pressure water and pumped water. The one closest to the pump prevents mains pressure water being forced into the pump and back into the tanks. The one closest to the Mains Pressure Inlet** stops pumped water from escaping through the inlet. Both together prevent water from draining from your HWS.

7) Mains Pressure Inlet - For simple installations this can be just a clip-on or screw-on hose fitting, but when a HWS is included and other pressure sensitive plumbing fittings you should include a pressure reducing device as the water enters your system. **Shurflo make two options that will suit here. The Shurflo incorporates its own non-return value, so the separate one shown in diagram would not be required.

8) Hot Water System - There are a number of versions, some electric only, some gas only, and some that will do both. You do not want to start your HWS unless it is full of water so the non-return valves will prevent this from happening. We recommend the Suburban range unless space or access does not allow them to be used.

9 & 10) Mixer Taps & Shower Mixer Taps - Any number of mixer taps can now be included in your plumbing system once you have your flow of hot and cold water. You can use household taps but they will weigh much more than the RV speciality versions and they are more bulky.

Other options: With an alternate layout it is possible to fill your tanks directly from the mains pressure inlet (without using water fillers on the side on your RV) but you will not be able to top-up your tank with a bucket.
Also many larger RVs have a completely separate tank and pump for fresh drinking water in addition to the above. They may also included a water filter to remove taste and bacteria. In this case you cannot share the water pump between two systems.

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13 Comments

  • comment-avatar

    Tania

    Excellent description of how it all works

  • comment-avatar

    Louis

    Great summary of how the plumbing in a caravan works. Best I have found on the net. Complements their great purchasing service.

  • comment-avatar

    kevin

    a very good DIY presentation to follow with confidence, would like to see the grey and black tanks running in conjunction with this including all the breathers etc. thanks all the same,

  • comment-avatar

    Bob Hayward

    My motor home has a shureflow pressure limiting device in the main cold water supply line. I need to adjust it but can find no data.

  • comment-avatar

    John

    Maybe spell Shurflo correctly and you will find an abundance of information all over the net

  • comment-avatar

    Bob Hayward

    Thanks John but I had already tried that one. I even tried spelling it in English rather than corporate jargon. Didn't get anywhere with sure flow either.

  • comment-avatar

    Dan

    Very easy to find UU.UU.UU.doityourselfrv.com/adjusting-pressure-switch-on-shurflo-water-pump/ change u to w

  • comment-avatar

    James

    Very good description - many thanks!

  • comment-avatar

    Wim baas

    On our Jayco Sterling 2012, I replaced the water inlet as it was perished. Unfortunately when we used the 12 volt system and had water come out the hose connection so the only way to use it was run a hose from inlet and cap it off. Once Home I checked out looking for the non return valve and low and behold, the non return valve is located inside the back of where the hose connection goes. Put old fitting back on and problem solved.

  • comment-avatar

    Roy

    Simple and easy to understand diagrams. Good for getting a mental picture if you really don't know where to start with the plumbing. The links back to products on your site are great too. Thanks

  • comment-avatar

    norm

    my 1995 Bailey van ( imported ) has shower etc but it does NOT have ANY water tank fitted. it comes with a 15 ltre container that one inserts a hose connected to the pump ...... SO buyers beware older vans may be the same . I am about to install two connected tanks one under each bed. so all the plumbing should be straight forward .. P S . NO external hose connecting fitting or tank fill fitting on the van either .

  • comment-avatar

    Bob Hayward

    Thanks for all 5he helpful suggestions. Been on the road almost two weeks and the pressure limited device is working OK. So far we’ve managed fine without using the shower, what with van parks and the wonderful Queensland thermal pools. We will need to use the shower tomorrow and that will be the real test. The adjustment I ended up making before we left home was to loosen the screws inside the device. Probably not the best way but in the absence of any specific instructions it was the best I could do.

  • comment-avatar

    Stephane

    Hi great description. I am about to buy my plumbing set up and I was wondering in sub zero climate is there anything I should get or do in my system in case the water freeze? Thanks

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