What do these signs mean?

Why would someone post these signs? Explain your ideas in detail on the discussion page.


external image 3604_signs.jpg
external image 4288_signs.jpg


external image Non-Potable-Water-Caution-Sign-S-2839.gif
external image JUST-SAY-NO.gif


external image Non-Potable-Water-Notice-Sign-S-2844.gif
external image SuperStock_1566-462221.jpg


external image 23311_148093441873841_6677_n.jpg
external image non-potable-water-sign-s-2842.gif


external image Industrial-Non-Potable-Water-Sign-S-2823.gif
external image nonpotable.jpg


external image Adoucisseur_eau_04_eau_adoucis_eau_non_potable.jpg

external image 4032856.jpg