How To Wire A Microswitch Tap And Water Pump

How To Wire A Microswitch Tap And Water Pump

How To Wire A Microswitch Tap And Water Pump


I know that the electrical part of the campervan build can be a little confusing for some, but this one is a real brain teaser, and even I have to pause and think about it occasionally. 

The other day I was installing a new tap and pump system to a van, and it had been a while since I fitted a water system – all of a sudden, my brain went blank, and I was staring at 3 sets of wires and feeling slightly embarrassed. Thankfully, normal cognitive function resumed, prompting me to create a wiring diagram to help others who may have the occasional brain freeze.


So who is this post for? 

Well, if you have a tap with a micro switch and a submersible pump to bring water from your onboard tank when you turn on the tap, then this post will help you wire it all together from a single live feed. What equipment will you need? 

  1. Tap with a microswitch
  2. Submersible 12v pump
  3. Fused live feed from your battery
  4. The ground wire from chassis or negative busbar
  5. 3-way connector block

You can run a live feed from your fuse box or use an inline fuse if running from the battery terminal. 


What wire goes where? 

Here goes: 

Step 1: Connect your live feed from the battery to the positive wire from the tap (they should be labeled). 

Step 2: Connect your negative wire from the tap to the positive wire of the pump 

Step 3: Connect the negative wire from the pump to the ground wire from your negative busbar or chassis. 


What Is A Micro Switch Tap In a micro switch system, each tap contains a tiny switch? 

Turn the tap on, and the water pumps run, turn the tap off, and the pump stops. There is a micro switch under every tap, both hot and cold, so there could be six more to go wrong.

You know if it’s a micro switch by a slight click when you turn the tap on and off. Microswitches were used on older vans, say pre-1995 (ish). If a tap won’t operate, the pump turns another tap on slightly. This should switch the pump on, and water will come out of the first tap and most likely points to a faulty micro switch or wiring fault. The micro switch is at the bottom of the tap. You will need to remove the tap and maybe best replace the whole tap. 

A pressure-switched system is more straightforward than a micro-switched one as it only has one pressure switch which switches the pump. The taps turn the water flow on or off or up or down. When a tap is turned on, the pressure switch detects that the pressure in the pipes has reduced and runs the pump. Turn the tap off, and the pressure switch detects the rise in pressure and stops the pump. 

If there is a slight leak in the pipes, the pump will occasionally run to maintain the pressure even if the tap is not open. The pressure switch works best if there is a surge damper and smooths out the pumping. You can adjust the flow from the tap from very slow to fast.

You need to adjust the pressure switch correctly. To do this, turn on a cold tap and close it slowly until the water comes out at a slow trickle. Then adjust the pressure switch until it can be heard constantly switching on and off. 


As a large-scale electronic component product manufacturing service provider in China, Unionwell has taken the lead in the industry to pass the national high-tech enterprise certification. The professional business scope includes the precision micro switch, automobile switch, waterproof switch, and various precision metal and plastic products. 

The design, manufacturing, sales, and service of various series of products are integrated to complete the supply in the middle and high-end markets. 

Welcome to visit our website for more details on the micro switch:    and send an email to  

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