Patio Cleaning

Having tried a number of pressure washers on our Indian sandstone patios, I decided to beg, borrow or steal an industrial pressure washer with a good litres per minute delivery. The car dealership where I occasionally help out had one - 45 LPM - perfect.

Now 45 LPM is way beyond the delivery rate of your normal domestic tap, but far in excess of the 4 to 6 LPM of many of the pressure washers you can in Lidl or Aldi. While my garden tap can't deliver 45 LPM, a 45 LPM washer takes advantage of the full delivery rate, whatever that may be.

The delivery rate of a standard UK tap is between 4 and 6 LPM, with some going as high as 10. I measured our garden tap delivery and it filled a 12L bucket in exactly 1 minute - better than the usual domestic delivery. There again, we have a good head of water from our local reservoir.

If you must have a standard pressure washer, get one that's capable of 10 to 12 LPM, hoping your garden tap will deliver that flow rate (or simply measure it with a bucket, as I did). 120 PSI is generally enough pressure. People are seduced by the PSI and end up buying expensive jet sprays with an advertised PSI of 160, only to get 6.5 LPM, which is pitiful and doesn't even take full advantage of what's coming out of the tap.

I went to the dealership at 7am on a Sunday morning and then discovered the pressure washer had a blue, caravan-style hookup connection, rather than a normal 3 pin plug (the yellow, 3 pin caravan style plug is a 110V connector for certain power tools). Not an issue, as we have a hookup 3pin to standard 3 pin converter for the motorhome. It weighed a surprising amount for its size - I could only just lift it into the car.

Having disconnected all the hoses, it took me an hour to reconnect them at home - they obviously hadn't been disconnected for years and I had to do some maintenance on them.

The difference in cleaning power was phenomenal. The commercially available pressure washers just don't touch the algae.

It's not perfect, but after 9 years in situ I can't really expect it to be, but it's a vast improvement.

Given the pressure washer is limited by the tap delivery, I dare say I could get a higher pressure by using a water butt to provide the water, with the pressure washer using suction to deliver the input side at full rate.

To that end I used polyurethane resin and fibreglass to caulk a leak in an old water butt that was destined for the recycling and bought a ball valve for it, adding a push-fit hose connection so I could connect the garden hose to it. The hose will fill the butt and the ball valve will cut off the inflow automatically when it's full, ensuring I have a decent reservoir for the 45LPM pressure washer the next time I use it, although I dare say it will empty the butt quite fast. A standard water butt is 165 litres, which will last no longer than 3.6 minutes - slightly longer as the ball cock opens and starts to fill the butt. An IBC would be a better solution.

No leaks and the ballcock works perfectly.

I still have to do the front patio and will try using a water butt this weekend to see if I can obtain a greater blasting power, but I'll have to be careful not to blast the grout from between the paving slabs.

I thought the water butt might even improve the delivery of my Titan TT2200P pressure washer, but that only has a 500 litres per hour delivery rate, which is 8.33 LPM, so it's not even taking full advantage of the flow coming from the tap and the water butt won't make the slightest difference. I did try it, but it was as suspected. There was also a problem with priming the pump, as it takes a while for the suction to get going - perhaps taking the water from the bottom via the tap, where there's a good head of water, would be better than putting the hose in from the top.