Sodium and phosphorus combination
While many land application systems require not only the minimisation of sodium in the wastewater (greywater) hat may be used for irrigation, there may also be a requirement to minimise phosphorus because the soils have low phosphorus sorption capacity (ability to lock up phosphorus and slow down its movement out of the soil). The figures below indicate the combination of sodium and phosphorus on the same graph. Two bars are represented for each product, the blue bar representing the sodium load (g/wash) and the red bar showing the phosphorus load (g/wash). The products are ranked in order of sodium load as this is often the more important consideration for land application.
The interpretation of the graph depends upon your requirement to minimise either sodium or phosphorus or both.
Table LF5-Na&P is a ranking of the sodium and phosphorus loads for the liquids when mixed at the rate for front loading washing machines (75 L per full wash).
Table LT5-Na&P is a ranking of the sodium and phosphorus load for the liquids when mixed at the rate for top loading washing machines (150 L per full wash).
Assessment
While it may not be possible to choose products with no sodium, there are many products that have very low levels of sodium that may not cause problems with either plants or soils in most locations (very short blue bar). It is, however, possible to choose very low sodium products that have no phosphorus (red bar absent).
It is interesting to note that the two products that are designed specifically for front loaders (block letters), that these have not only the highest sodium load but also the largest phosphorus load.