Which Pressure Washer Hose Connector & Coupling Fitting to use?


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If you have bought or are buying a pressure washer then the only other thing you need to consider is the water supply to this, this could be via a outdoor tap, bucket of water using a function pipe, or connected to a water butt. If you have an outside tap then you may already have a hose pipe connected to this.

If you don’t then you will need to purchase one if you want to hook it up to your pressure washer, this gives you more flexibility allowing you to have the pressure washer on your front drive, if the outside tap is to the rear of your property.

Which Hose Pipe Connector to use?

Most pressure washers use the same style and design push and click connectors, this could either be a Karcher or Nilfisk connector, or a Hozelock connector, the way they work is the same.

However, due to them being made by different companies, they are all made to work with other connectors they produce, and what you will find is that there are very slight and marginal differences between them, in size and fit.

By mixing different branded connectors you may find slight leaks where they join, or poor water flow, or at worst the connectors just not holding and with the pressure washer on the connects blowing off.

Karcher Hose Pipe Connector

If you own a Karcher pressure washer be it a new or older model of the K2, K4, K5 or K7 power washer range, then the Kärcher Hose Connection Set For Pressure Washers is ideal.

Karcher Hose Pipe Connector

As it says it is designed specifically for use with pressure washers. The set comes with a 10m of Primo flex hose and all the connectors you need, you get a tap adapter that screws onto the outside tap, and then two universal hose connectors of which on come with aqua stop.

These are designed specifically for Karcher pressure washers making the joint and connection a perfect match.

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Nilfisk Hose pipe connector

Unlike Karcher, Nilfisk don’t offer a special hose pipe kit for their pressure washers, they are supply some plastic connections to get you started but these are not the best.

We would advise buying some metal connectors, these could be the Hozelock Pro Metal Hose End Connector or we recommend the Gardena Premium Metal Hose Connector which we talk about further below. Metal connectors will give a stronger and more robust connection unlike plastic connectors which can easily be blown off when using with a pressure washer.

Will karcher accessories fit Nilfisk Pressure Washers?

No. Karcher and Nilfisk have different fitments, it is important to buy the correct fittings for your pressure washer to ensure a tight fit and seal so there are no leaks.

Avoiding Water Stop Connectors

Auto shut off connectors can be bought and used, however when it comes to using with a pressure washer it can effect the flow of water meaning that you may not get the maximum flow of water output that your pressure washer can handle. This will be because the auto shut off effects the flow of water making it slowly before it reaches the pressure washer, so with this in mind we advise avoiding these types of hose pipe connectors.

Best Hose Pipe Connector

Sometimes it pays to pay a little more, and when it comes to using it with a pressure washer a solid, strong and robust connection is vital. Most standard hose pipe connectors from many popular brands are made from plastic, however paying a little more allows you to purchase a metal ring hose connector that is more robust and gives a better and longer lasting connection.

Gardena Premium Metal Hose Connector

This is a very high quality premium hose connector that uses the commonly found pull releases the connection, and push and click fixing.

Gardena Premium Metal Hose Connector

It comes with a grooved soft plastic grip, a protective rubber ring and stable clamping nut made from high quality metal giving a strong connection. The Gardena Premium Metal Hose connector is suitable for 12mm – 13mm diameter hoses and comes with a 2 year warranty.

It is well made and provides a great seal and joint. These maybe slightly more in price but they last longer and are more robust.

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My hose keeps blowing off!

If you have your pressure washer all set up but find the hose pipe keeps blowing off when using it then the likely reason will be that you are using plastic connectors that are certainly not the best. We would advise buying some metal connectors like mentioned about such as the Gardena Premium Metal Hose Connector which will hold better and should prevent the pipe blowing off.

5 Comments

  1. mr T .PARRIS

    why do karcher advertise a hose kit with aqua stop especially made for pressure washers ,when they tell you not to use them as they will damage a power washer ? I would like someone with better knowledge than me to comment on this please

    Reply
  2. Alan Shaw

    I would imagine the special Karcher Aqua Stop connector has a larger bore than the usual ones, so as not to restrict the flow through it when it is connected.

    Reply
  3. Stephen Ford

    I have read the content here and don’t see any comment that the auto-shut-off fitting will ‘damage’ the pressure washer. It says it will “reduce the flow rate”.

    It’s a shame that non-plumbers write this type of website content because they muddy the waters (almost a pun… 🙂 ) of the plumbing technology by using non-standard terms. An auto-shutoff fitting is one which prevents a flow back into the mains supply (backflow) in an effort to prevent your drinking water from being contaminated by devices connected to the water main. And in plumbing terms that is a “check valve”. It’s also called a “non-return valve” in other industries not related to domestic plumbing. The term “check valve” is the preferred term used in the Water Regulations, so IT WOULD BE NICE IF THE WEB MASTER WOULD REVIEW THE TERMINOLOGY HERE PLEASE…!!

    After all, the water going to the pressure washer is your and all your neighbour’s drinking water! So I assume you don’t want mucky cleaning water re-entering the water main. If it does and is traced to the householder there is a £5000 fine waiting to be had. The check valve is there to stop this backflow and the resultant water contamination.

    From what I’ve seen over the years, one of the least understood issues in domestic plumbing is flow rate and pressure. The consensus of opinion is that a high velocity water jet from any device (tap, pressure washer) equates to a high pressure. This is inaccurate and is the wrong focus altogether. The correct focus is both the velocity AND quantity of water jet. The ‘quantity’ is the flow rate. There is no point in a needle-sized jet of water at high velocity. A jet of water only cleans well when it’s a larger diameter; or more accurately a larger cross sectional area AND has a high velocity. So a simple test is “how quickly does it fill a bucket of water”. If it’s rattling out at high velocity and takes half an hour to fill a 5 litre bucket, it will be no use to man nor beast…

    But this is where the effect of your household pipework and fittings comes into play. The device will be designed to work at a specific inlet flow rate and inlet pressure. This means your water supply (including pipes and fittings) all the way from the stopcock at the property boundary, and all the way to the pressure washer inlet must supply this. And it’s very easy to measure. All that’s required is a lever valve at the hose connection to the pressure washer, and a pressure gauge behind the valve. The lever valve is fitted instead of the pressure washer. Open the valve to let the water flow at the value specified in the washer specification and read the pressure. It’s easy enough to record the time to fill a bucket and calculate the flow rate from that. Then check the pressure washer specification. I spotted 0.2Mpa at 7L/min in one Karcher spec. 0.2MPa is 2bar. The pipework in most houses will not deliver anything like that once it’s gone all the way down a long hose as well. That’s why the manufacturer supplies a large bore hose to reduce the flow resistance. I guess that their check valve connectors may have very light spring also to reduce the flow restriction.

    And back to backflow – The water regulations demand that we stop backflow. So a double check valve should be fitted to the water supply to an outside tap in all cases. It’s a rule in the Water Regulations. Karcher tell me that they recommend a single check valve on the hose as well. This is discussed next.

    There is a need to manage reverse pressures in the supply hose. Small volumes of water can be pushed back into the supply and at pressure washer pressures this will either blow the hose to bits and / or damage the pressure washer if not handled properly. Karcher say that the check valve must be on the tap end of the hose to allow the backflow to enter the hose at the pressure washer end. Then the hose must be long enough (have sufficient volume) to absorb the backflow volume without increasing the pressure in to the hose to a level that will cause rupture. There is also a device called an expansion vessel. It would not take much imagination to pipe up a small one, say 2 litres close to the supply connection to guarantee that the backflow volume is absorbed safely.

    I hope the reader feels more aware now of the requirements of the plumbing system to supply water to a pressure washer.

    Reply
  4. Peter

    So if I understand correctly, putting the aquastop on the pressure washer side can damage the pump, because the backflow water pressure won’t have anywhere to expand.

    I recently had to use another hose with metal couplings, one of them being aquastop on my ancient 1991 HDS 550c hot water PW. The aquastop was attached to the PW.
    I had never used such couplings before.
    After some 15 min the metal flange on the pump where the hose is attached to bursted and broke in half.

    I guess this was because of the pressure inside the pump couldn’t go back into the hose.

    I just bought a K5 that came with this Karcher hose set mentioned above that also has aquastop.
    The manual does mention that only metal couplings with aquastop should be avoided, still nowhere does it say that you shouldn’t put it on the PW side.

    I just find it baffling.

    Reply

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