Remote control of fluid-handling devices

A system, comprising:

• a first computer system disposed at a first fluid handling site, the first fluid handling site comprising a first pump, a first valve, and a first tank that handle a first fluid, the first tank having a first fluid-level sensor with which the first computer system is configured to communicate to obtain a level of the first fluid in the first tank, and the first computer system being configured to provide remote control of the first pump or the first valve;
• and
• a server system remote from the fluid handling site, wherein the server system has memory storing instructions that, when executed, effectuate operations comprising:
• receiving, with the server system, from the first computer, via a network, a first fluid level sensed by the fluid-level sensor;
• obtaining, with the server system, credentials from a first client computing device;
• determining, with the server system, based on the credentials, that a user of the first client computing device is authorized to interact with the first fluid handling site, wherein the server system hosts data about other fluid handling sites the user is not authorized to interact;
• after the determination, providing, with the server system, via the network, information by which a first client computing device presents a user interface indicating the first fluid level, the first client computing device being remote from the server system and the first computer system;
• receiving, with the server system, from the first client computing device, a first command to change a state of the first pump;
• and
• causing, with the server system, the first computer system disposed at the first fluid handling site to effectuate the command by changing the state of the first pump to a sequence of different target states that change over time.