Abstract: A mixing valve adapter is disclosed for a sink faucet with a mixing valve. An example mixing valve adapter includes an adapter body formed as a rigid unitary structure that does not flex so that the mixing valve is mounted rigid to the sink faucet without separately mounting the mixing valve apart from the sink faucet. The example mixing valve adapter also includes a first valve connection on the adapter body for connecting mixed cold and hot water from the mixing valve, and a first faucet connection on the adapter body for connecting the mixed cold and hot water to the sink faucet. The example mixing valve adapter also includes a second valve connection on the adapter body for connecting cold water from the mixing valve, and a second faucet connection on the adapter body for connecting the cold water to the sink faucet.