Abstract　 　 
The very few early known, strongly lensed high-z sub-mm sources (FIRAS10214, Cloverleaf, APM08279), played a very important role in the development of high-z submm/mm astronomy through pioneer detections of 0.85-1.2mm continuum and CO lines, and various high sensitivity studies allowed by their strong magnification. Herschel wide surveys, which will hopefully observe ~1000 deg², are discovering hundreds of similarly strongly lensed submm galaxies (e.g. Negrello et al. 2010). I will first review the current state of mm/submm follow-up of such Herschel lensed galaxies with IRAM and other facilities, for CO redshift determination, mapping mm continuum and CO lines with interferometers, measuring 1.2mm continuum flux density, etc. I will specially stress the case of the recent detection of H2O at IRAM/PdBI in two such sources at z=2.3 and 3.3 (Omont et al. 2011). These examples give an idea of the numerous studies allowed by strong lensing magnification and the enhanced capabilities of ALMA and IRAM/NOEMA, using this unique sample of hundreds of Herschel high-z lensed galaxies.