Get yourself one of these. Been in my bag and searched with no problems getting in anywhere. Holds a lot too so saves a small fortune.
https://www.amazon.co.uk/Umbrella-Flask-Smuggle-Overpriced-Queuing/dp/B0BKVYDKR1/ref=d_pd_sim_cn_sccl_3_4/261-7217021-7286068?pd_rd_w=1240Y&content-id=amzn1.sym.dba415a8-290b-4680-9db4-f0643b3ffd93&pf_rd_p=dba415a8-290b-4680-9db4-f0643b3ffd93&pf_rd_r=XRHMR7EJ1RGAGECPNKZF&pd_rd_wg=3nDGU&pd_rd_r=c662251d-6809-453e-a985-75f46402b07c&pd_rd_i=B0BKVYDKR1&psc=1 |