Shampoo Dilution Guide
Different shampoo brands have different dilution rates, and some formulas by the same brand, have different dilution rates than other formulas by the same brand. Most Bio-Groom formulas are 16:1 for example (16 parts water to 1 part shampoo), but their Econo Groom formula can go right up to 50:1.
Shampoo that can be diluted, does not have to be. Most can be used undiluted provided they have a low dilution rate (eg: 4:1). Many can be used straight out of the bottle at full strength. However very concentrated formulas with higher dilution rates (eg: 16:1 or higher), should always be diluted for best results. It's sensible to dilute when you can as it also offers significant savings. It can also prevent accidentally irritating a pet's skin, especially if they have sensitive skin.
If a shampoo is medicated, or has active ingredients, such as flea shampoo or medicated itch shampoo, always follow the instructions on the label about dilution rates. This is because it's been tested to work (eg: kill fleas) when used at the correct, diluted rate. Dilute too much and it may not work, use too concentrated and it may cause irritation.
Dilution rates by brand
The FIDOS range of shampoo and conditioner is formulated to be used straight out of the bottle, undiluted, except their formulas that say they are concentrates (such as their flea rinse and their cleaner). Fidos shampoo and conditioner already have a higher water content, and do not need to mixed or diluted first.
Most BIO-GROOM and PET HEAD formulas are concentrates, and can be diluted up to 16:1 (16 parts water to 1 part shampoo). That means to make a gallon (3.8 litres), you only need about 1 cup of shampoo! Bio-Groom Econo Groom can be diluted right up to 50:1 when used in a hydrobath (so just 1/2 a cup of shampoo is needed to make a gallon).
Another way to work it out, is how much would 1 litre of the product make? For example, a 1 litre of shampoo that can be diluted 16:1 would make 17 litres of shampoo (1 litre of shampoo + 16 litres of water = 17 litres). If that 1 litre cost you $10, by diluting it instead of using it straight out of the bottle, you'd save $160!
How long will diluted shampoo stay fresh?
Shampoo should always be used freshly diluted. Water has bacteria in it that can make pre-mixed shampoo or conditioner spoil over time if left too long. A general rule is to use pre-diluted shampoo within 24 hours in summer, or 48 hours at cooler temperatures (as bacteria grows faster when it's warmer).
One easy approach is to mix the shampoo and conditioner needed for the day, in the morning, then empty and clean out containers at the end of every day as a routine to avoid accidentally using spoiled product.
How do you easily mix shampoo at the right dilution rate?
You can get shampoo dispenser systems that do it for you. You set the dial on the unit to the dilution rate. The unit sucks up the right amount of shampoo and mixes it with water, as the water passes through the unit, freshly diluted, ready to use, and nothing gets wasted.
You can also buy dilution bottles. Most list all the common dilution rates on the side and you just fill to the line to match the dilution rate you want. Some you add shampoo to the correct level first, then top up with water, others you put the water in first then top up with shampoo. There's no 'right and wrong' with what's best, but the method of adding water first can avoid shampoo bubbling up (versus adding shampoo first, then adding water).
Does mixing with warm or cold water matter?
Yes, it's best to dilute using warm water rather than cold, or hot. Warm water mixes in better with most shampoo and conditioner concentrates. Shampoo may not mix with cold water, and very hot water can increase the speed that bacteria grow.
Some conditioner tends to be quite thick, so some can be harder to fully mix in to the water than others, so a combo of warm water plus a stick blender is a handy way to get it properly mixed in if you find that happens.