I prefer this alternate version of the quote, which someone may have made up as it does not seem verifiable: "The blood of the covenant is thicker than the water of the womb," which has the opposite meaning of the standardly quoted phrase. I wrote this tanka about three years ago:

Blood or water bonds

Bleed with friends from family

Blood clots water flows

Family oft gaslights me

Yet one clap from sis tears flow

If you want to read the short discussion: https://medium.com/know-thyself-heal-thyself/of-blood-and-water-c3f8645c856f