<\/p>
When buying a waterproof jacket for running<\/a> or cycling<\/a>, you may notice a number in the product specs, followed by mm and sometimes the abbreviation of HH. This is a hydrostatic head rating.\u00a0<\/strong><\/p>\n Not sure exactly what that is and why it\u2019s important? Don\u2019t worry, read on to find out\u2026<\/p>\n Hydrostatic head is a measurement that\u2019s used to determine how waterproof a fabric is.<\/p>\n The figure is based on a water column test. Traditionally, a column of water would be placed on top of a fabric and increased in volume (and thus pressure) until it penetrated the fabric.<\/p>\n The height of the water column at that moment is then taken and applied as a measurement in millimetres, which is the hydrostatic head rating.<\/p>\n In modern times, the test is carried out by a machine that will increase the pressure of the water without needing a column of water stretching skyward.<\/p>\n <\/p><\/div> <\/section> Hydrostatic head ratings are normally quoted for products that claim to be waterproof.<\/p>\n For triathletes, waterproof jackets (for both running and cycling) and dry bags<\/a><\/strong> will be where you\u2019re most likely to come across a hydrostatic head rating, though you could also spot them when buying a waterproof running hat<\/a><\/strong>, for example.<\/p>\n Outside of the multisport world, you\u2019d also find hydrostatic head ratings quoted for things like tents.<\/p>\n For something to be classed as waterproof in the UK it has to have a minimum hydrostatic head rating of 1,500mm.<\/p>\n However, most waterproof jackets will exceed this, with figures of over 10,000mm very common, which is a good benchmark.<\/p>\n That being said, a hydrostatic head rating isn\u2019t the only thing you need to take into consideration. To keep you dry a garment also needs to stop water coming through the seams, too. This is normally achieved via taped seams.<\/p>\n Of course, as hydrostatic head ratings go higher the weight and weave of the fabric often increase too, which can negatively affect both breathability and comfort, particularly when running.<\/p>\n It\u2019s also worth noting that garments you\u2019d expect to experience a lot of abrasion will typically have a higher hydrostatic head to deal with the increase in pressure.<\/p>\n Water column tests, which determine hydrostatic head, also don\u2019t take into account how performance wanes over time or how the fabric performs in real-world conditions, so it\u2019s always worth checking out expert and user reviews before investing.<\/p>\n Top image credit:<\/strong> Caia Image\/Getty Images<\/p>\n <\/p><\/div> <\/section> <\/body><\/html>\n By Rob Slade Published: Wednesday, 14 December 2022 at 12:00 am When buying a waterproof jacket for running or cycling, you may notice a number in the product specs, followed by mm and sometimes the abbreviation of HH. This is a hydrostatic head rating.\u00a0 Not sure exactly what that is and why it\u2019s important? Don\u2019t […]<\/p>\n","protected":false},"author":24,"featured_media":19988,"template":"","categories":[1],"acf":{"readingTimeMinutes":"3"},"uagb_featured_image_src":{"full":["https:\/\/c01.purpledshub.com\/uploads\/sites\/47\/2022\/12\/what-is-hydrostatic-head.jpg",1200,800,false],"thumbnail":["https:\/\/c01.purpledshub.com\/uploads\/sites\/47\/2022\/12\/what-is-hydrostatic-head-150x150.jpg",150,150,true],"medium":["https:\/\/c01.purpledshub.com\/uploads\/sites\/47\/2022\/12\/what-is-hydrostatic-head-300x200.jpg",300,200,true],"medium_large":["https:\/\/c01.purpledshub.com\/uploads\/sites\/47\/2022\/12\/what-is-hydrostatic-head-768x512.jpg",768,512,true],"large":["https:\/\/c01.purpledshub.com\/uploads\/sites\/47\/2022\/12\/what-is-hydrostatic-head-1024x683.jpg",800,534,true],"1536x1536":["https:\/\/c01.purpledshub.com\/uploads\/sites\/47\/2022\/12\/what-is-hydrostatic-head.jpg",1200,800,false],"2048x2048":["https:\/\/c01.purpledshub.com\/uploads\/sites\/47\/2022\/12\/what-is-hydrostatic-head.jpg",1200,800,false]},"uagb_author_info":{"display_name":"importmanagerhub@sprylab.com","author_link":"https:\/\/c01.purpledshub.com\/220triathlon\/author\/importmanagerhubsprylab-com\/"},"uagb_comment_info":0,"uagb_excerpt":"By Rob Slade Published: Wednesday, 14 December 2022 at 12:00 am When buying a waterproof jacket for running or cycling, you may notice a number in the product specs, followed by mm and sometimes the abbreviation of HH. This is a hydrostatic head rating.\u00a0 Not sure exactly what that is and why it\u2019s important? Don\u2019t…","_links":{"self":[{"href":"https:\/\/c01.purpledshub.com\/220triathlon\/wp-json\/wp\/v2\/rss_feed\/19987"}],"collection":[{"href":"https:\/\/c01.purpledshub.com\/220triathlon\/wp-json\/wp\/v2\/rss_feed"}],"about":[{"href":"https:\/\/c01.purpledshub.com\/220triathlon\/wp-json\/wp\/v2\/types\/rss_feed"}],"author":[{"embeddable":true,"href":"https:\/\/c01.purpledshub.com\/220triathlon\/wp-json\/wp\/v2\/users\/24"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/c01.purpledshub.com\/220triathlon\/wp-json\/wp\/v2\/media\/19988"}],"wp:attachment":[{"href":"https:\/\/c01.purpledshub.com\/220triathlon\/wp-json\/wp\/v2\/media?parent=19987"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/c01.purpledshub.com\/220triathlon\/wp-json\/wp\/v2\/categories?post=19987"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}What is a hydrostatic head?<\/strong><\/h2>\n
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What gear has a hydrostatic head rating?<\/strong><\/h2>\n
What\u2019s a good hydrostatic head rating?<\/strong><\/h2>\n
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