A liquid testing device for determining the value of at least one property of a liquid. The liquid testing device includes a planar base and at least one test section, located on the planar base, with a reference color section located adjacent to the test section, which exhibits a color according to the value, as a result of reaction of a reagent with the liquid. The reference color section includes a plurality of different reference colors arranged for easy visual color comparison with the test result. The reference color section is placed adjacent to and in contact with the test section, with the test section having sufficient length so that it substantially encompasses the entire reference color section with its plurality of different reference colors. Thus, when the test section exhibits a reaction color, the visual comparison is simplified since the reference color which matches the reaction color becomes substantially visually merged and self-aligned therewith.