"Parts per" notation refers to proportionate measurements and not defined units of measurement. One part solution to four parts water means that proportionately, there should be four times as much water as solution, no matter how big or small the quantities are. This type of measurement is often used in chemistry, physics and cooking.
Using Small and Large Containers
Fill your small container with the solution and put it into the large container. This is the one part solution.
Rinse the small container.
Fill the small container with water and empty it into the large container and repeat three times. These are your four parts water.
Mix the formula in the large container.
Using a Graduated Cylinder
Determine the total amount of fluid you need.
Divide the total amount by five to find the amount of each part. For example, if you need 50 milliliters of fluid, each part will be 10 milliliters.
Measure one part of solution into the cylinder (in our example, that would be 10 milliliters).
Measure four parts water (in our example that would be 40 milliliters).
Pour the formula into a beaker to mix, if necessary.
For a precise measurement using a graduated cylinder, lower yourself so that your eyes are at the level of the cylinder. Measure from the lowest part of the meniscus (the curved line of the water).
If you are using dangerous or toxic substances, use safety equipment such as gloves and goggles.