Zamioculcas zamiifolia
ZZ plants store water in thick underground rhizomes, so they tolerate long gaps between waterings. Rot from too much water is far more likely than thirst.
Short answer: for a ZZ plant, with the starting settings below (a 6 inch pot with a drainage hole), check the soil about every 12 to 18 days in spring and summer and every 18 to 27 days in winter, and water when the top two inches of soil are dry. Give it a full drink until water runs out the bottom.
Your answer
Water when the soil reaches this point
How it shifts through the year
Check the soil about every 12 to 18 days in spring and summer and water only when the top two inches of soil are dry. In winter, growth slows and soil stays wet longer, so expect roughly 18 to 27 days between checks. Always confirm with your finger first.
Water slowly until water runs out the drainage holes, then empty the saucer within an hour. The right amount depends on pot size, so go by drainage and how dry the soil is, not a fixed measure. A full soak followed by a long dry-down suits them, since they store water in underground rhizomes.
A ZZ plant can go weeks without water because the rhizomes store it. A long dry spell is safer than soggy soil.
Overwatering is the most common cause. Let the soil dry out fully and check that the pot drains.
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Related guides
Estimates use rules of thumb. Always confirm with your finger: push it about an inch into the soil before you water.