---
title: "Flexitank contamination after a caustic wash: how do you verify it is clean? — LiangduSyrup"
url: "https://liangdusyrup.com/forum/flexitank-contamination-after-a-caustic-wash-how-do-you-verify-it-is-clean/"
date: 2026-09-21
---

# Flexitank contamination after a caustic wash: how do you verify it is clean?

Flexitanks are economical for liquid syrups, but a reused or poorly cleaned tank can carry odour or residue into a food-grade load. We want to hear how others verify cleanliness before loading.

- Do you require a swab test, a rinse-water test, or a visual inspection?
- Which certificates or declarations do you insist on from the flexitank supplier?
- Have you ever rejected a tank, and what tipped you off?

Any checklists or rejection criteria you are willing to share would be genuinely useful.