The temperature of concrete can be monitored by a temperature probe. Typically, large volumes of concrete such as are typically carried in mixer trucks or mixed in industrial concrete production drums have a relatively stable, or slowly varying temperature, given the high thermal capacity of concrete. A sudden change in temperature can thus be attributed to an external event. A sudden addition of even a relatively small amount of water for instance, which has an even higher thermal capacity, can produce a notable sudden change in temperature. Examples where the detection of the addition of water can be particularly useful in the production and/or transport of concrete are provided herein. Moreover, if the temperature of the added water is known, and the quantity of concrete is also known, the sudden difference in temperature can be correlated to a volume of added water.