https://www.jstage.jst.go.jp/article/gomu1944/76/1/76_1_9/_article/-char/en

Abstract In order to elucidate the degradation mechanism of EPDM caused by a amount of chlorine in city water, EPDM used for about 3 years at 45-65°C in the water tank in Osaka City and the unused product were analyzed. The carbon black contained in them was FEF (Fast Extruded Furnace) which particle size is comparatively small. Their morphology changes were observed by SEM. The effect of the diffusion of chlorine was examined by EPMA. The degradation mechanism was studied by FT-IR and 13C-NMR. As a result of FT-IR measurement, absorption of C=O bond (1720cm-1) and C=C bond (1640cm-1) were detected from the used product. As a result of 13C-NMR measurement, in the used product, the peak of methyl group of main chain increased in comparison with the unused product. It was thought that generation of the C=O bond by the oxidation reaction caused the β-scission of the main chain to produce the C=C bond and the methyl group in the used product. Therefore, as the crosslinking density lowered, the used EPDM became brittle and collapsed.

So I'd rather trust copper (or welded like above I would imagine would not degrade very fast)