Verses 14-16 present several sample cases of pollution, and verses 17-19 give the procedure for purifying those who were affected. So some translations may wish to begin a new paragraph here (so Good News Translation, New International Version, New Living Translation).

For the unclean they shall take some ashes of the burnt sin offering: The unclean refers to “the unclean person” (Alter), namely, anyone who was polluted under the circumstances mentioned in verses 14-16. The referent for the pronoun they is indefinite. This person was probably a layman and not a priest because participation in this ritual caused impurity. The ritual could be performed by anyone who was ritually clean. For languages in which the subject needs to be specified, Contemporary English Version provides a helpful model by beginning this verse with “Before you can be made clean, someone who is clean [supplied from verse 18] must take….” Some ashes of the burnt sin offering refers to the ashes from the red cow that were kept in a ceremonially clean place outside the camp (see verse 9). For sin offering, see verse 9 and 6.11. Good News Translation provides a helpful model for this whole phrase, saying “some ashes from the red cow which was burned to remove sin.” In light of the discussion on verse 9, it is even better to translate “some ashes from the red cow that was burned to purify those who have become unclean” (similarly De Nieuwe Bijbelvertaling). Good News Translation makes it explicit that these ashes were not only taken but also “put in a pot” before water was added.

And running water shall be added in a vessel: Running water is literally “living water,” which refers to “fresh water” (Good News Translation). In the desert it would probably have been “spring water” (Contemporary English Version; similarly De Nieuwe Bijbelvertaling), coming from a natural source, not a cistern. This water had to be added to the ashes so that they could be more easily applied to the person needing purification.

Quoted with permission from de Regt, Lénart J. and Wendland, Ernst R. A Handbook on Numbers. (UBS Helps for Translators). Miami: UBS, 2016. For this and other handbooks for translators see here .