This formula from Tanaka et al. (2001) calculates the density of water as a function of temperature. The base density of 1000 kg/m³ (see physics::si::kWaterDensityBase) is adjusted by a temperature-dependent correction factor. The result is converted to lb/gal using physics::conversions::kKgPerM3ToLbPerGal.

\begin{equation}\label{eq:water-density-tanaka} \rho_w = 1000 \left[1 - \frac{(T_C + 288.9414)}{508929.2 (T_C + 68.12963)} (T_C - 3.9863)^2 \right]\end{equation}

Symbols

\(\rho_w\)	Water density \([\unit{ \kilogram\per\meter\cubed}]\)
\(T_C\)	Average water temperature \([\unit{ \degreeCelsius}]\)
\(1000\)	Base water density - see physics::si::kWaterDensityBase \([\unit{ \kilogram\per\meter\cubed}]\)