What size bucket do you need to wash a car?
By Ollie B - SoapX Ltd.
Most advice on the two bucket method says to use two buckets and stops there. Size matters more than you would think. A bigger bucket keeps the water cleaner for longer, gives the mitt room to move and makes the shampoo easy to measure. Here is what to look for.
What size bucket do you need to wash a car?
Twenty litres for each bucket. That is deep enough to cover a grit guard with plenty of clean water above it, and it holds enough to wash a whole car without a refill. A typical household bucket holds 10 to 14 litres.
Why a bigger bucket is safer
- More water means cleaner water. The same amount of dirt spread through twice the water takes far longer to turn it cloudy.
- Depth above the grit guard. A guard stands a few centimetres off the base. In a shallow bucket the mitt ends up working right on top of the dirt it has just dropped.
- Room to move. You need space to rub the mitt across the guard and to dunk it without water slopping over the side.
- Easier measuring. A known volume makes the dilution simple, so you use the right amount of shampoo every time.
How much water and shampoo to put in
You do not have to fill a 20 litre bucket to the brim. About three quarters full leaves room for your hand and stops it spilling when you carry it.
| Water in the WASH bucket | Shampoo at 1:200 | Shampoo at 1:100 |
|---|---|---|
| 10 litres | 50 ml | 100 ml |
| 15 litres | 75 ml | 150 ml |
| 20 litres | 100 ml | 200 ml |
No.05 Contact Shampoo is mixed at 1:200 in the Summer, Winter and Delicate formulas and at 1:100 in Extreme. The dilution ratio calculator works it out for any amount. The RINSE bucket gets clean water and nothing else.
How much water does a two bucket wash use?
Two full 20 litre buckets hold 40 litres between them. For comparison, Waterwise puts one hour of hosepipe use at 1,000 litres, which works out at about 170 litres for ten minutes with a running hose. The sources are on our car wash run off facts and figures page.
You will use more than the buckets if you pre rinse and rinse with a hose or pressure washer. During a hosepipe ban, our bucket only routine keeps the whole wash to the two buckets plus a few watering cans.
What else to look for in a wash bucket
- A grit guard that fits. Too small and it slides around. Too big and it will not sit flat. Our guide to whether grit guards work explains what the guard adds.
- A lid. It keeps grit out between washes and turns the bucket into storage for your mitts and bottles.
- A strong handle with a grip. Twenty litres of water weighs 20 kg, so a thin wire handle soon hurts.
- Clear marking. WASH and RINSE by colour or by label, so the two never get mixed up.
- Tough, smooth plastic. Smooth sides rinse clean and do not hold grit in scratches.
Our 20 litre wash bucket is food grade HDPE with a steel handle, a grip and a grit guard that fits. The Two Bucket Kit pairs an orange WASH bucket with a black RINSE bucket, each with a grit guard and a snap on lid.
Can I use any bucket?
Yes, if it is clean. Any two buckets count. Avoid one that has held cement, plaster, sand or garden soil, because grit hides in the scratches on the inside. Soft, flexible tubs are awkward too, as they fold when you carry them full.
Do both buckets need to be the same size?
No. If one is bigger, make it the RINSE bucket, since that is the one doing the dirty work.
Quick answers
What size bucket is best for washing a car?
Twenty litres. It covers a grit guard with plenty of clean water above it and holds enough to wash a whole car without a refill.
How much shampoo do I put in a 20 litre bucket?
At 1:200 it is 100 ml in a full 20 litre bucket, or 75 ml if you fill it to 15 litres. At 1:100 it is double that. Always follow the label on your shampoo.
How full should I fill a wash bucket?
About three quarters full. That leaves room for your hand and the mitt and makes the bucket easier to carry without spilling.
How heavy is a full 20 litre bucket?
About 20 kg plus the weight of the bucket. Fill it close to where you will use it.
How much water does the two bucket method use?
The buckets hold 40 litres between them when full. Add whatever you use to pre rinse and rinse the car.
Do car wash buckets need lids?
Not for the wash itself. A lid is for storage. It keeps grit out of the bucket between washes and gives you somewhere clean to keep your kit.
Kit for this job
- 20L Wash Bucket with Grit Guard, single or Two Bucket Kit
- No.05 Contact Shampoo
- Ultra Plush Microfibre Wash Mitt
- Starter Wash Kit
More from the Journal
Always read the label. Directions, dilutions and safety advice for every product are here:
