{"id":30,"date":"2026-09-08T09:00:00","date_gmt":"2026-09-08T01:00:00","guid":{"rendered":"https:\/\/frpwatertank.co\/index.php\/2026\/09\/08\/how-to-size-a-water-tank\/"},"modified":"2026-09-08T09:00:00","modified_gmt":"2026-09-08T01:00:00","slug":"how-to-size-a-water-tank","status":"publish","type":"post","link":"https:\/\/frpwatertank.co\/index.php\/how-to-size-a-water-tank\/","title":{"rendered":"How to Size a Water Tank: A Practical Engineering Checklist"},"content":{"rendered":"

Tank sizing goes wrong in a predictable way: someone takes the daily demand, multiplies by a round number, and ends up with a tank that is either too small on the hottest day of the year or 40% oversized and three times the foundation cost. Here is the checklist our engineers actually use.<\/p>\n

1. Start with peak hour, not daily demand<\/h2>\n

Storage exists to absorb peaks, so size on the peak hour or peak day \u2014 not the annual average. For a hotel, peak hour is typically 12\u201315% of daily demand. For a hospital it can reach 20%.<\/p>\n

2. Add the fire reserve separately<\/h2>\n

Fire storage is usually governed by the fire authority, not by consumption: commonly 1\u20133 hours at the design fire flow. Critically, fire reserve must be non-consumable<\/b> in normal operation.<\/p>\n

3. Do not forget dead storage<\/h2>\n

Allow 5\u201310% at the bottom that the outlet cannot reach, plus the freeboard at the top above the high-level alarm. A tank quoted as “100 m\u00b3” may deliver only 88 m\u00b3 of usable water.<\/p>\n

4. Check the refill rate against the peak<\/h2>\n

If the incoming main can only deliver 8 m\u00b3\/h and the peak draw is 22 m\u00b3\/h, you need at least 14 m\u00b3 of buffer per peak hour plus the duration of the peak. This calculation, not the daily total, usually sets the real size.<\/p>\n

5. Allow for growth and compartmentalisation<\/h2>\n
    \n
  • Growth:<\/b> add 15\u201325% if the building has an expansion plan \u2014 or add a bay later.<\/li>\n
  • Compartmentalisation:<\/b> two compartments let you clean or repair one half while the other stays in service.<\/li>\n<\/ul>\n

    Quick reference<\/h2>\n

    Office building: 25\u201340 L per person per day, 1 day storage. Hotel: 200\u2013350 L per room per day, 1\u20132 days. Hospital: 400\u2013700 L per bed per day, 1\u20132 days. Residential: 120\u2013200 L per person per day, 1\u20132 days.<\/p>\n

    Then check the physical fit<\/h2>\n

    Volume is only half the answer. A 500 m\u00b3 tank at 5 m height needs a 100 m\u00b2 footprint; at 3 m height it needs 167 m\u00b2. Before you fix the capacity, confirm the footprint, the clear height for panel assembly, the door width and the crane position.<\/p>\n","protected":false},"excerpt":{"rendered":"

    Peak demand, fire reserve, dead storage, expansion allowance \u2014 the five factors that decide your real tank volume.<\/p>\n","protected":false},"author":1,"featured_media":18,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[10],"tags":[],"class_list":["post-30","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-technical"],"_links":{"self":[{"href":"https:\/\/frpwatertank.co\/index.php\/wp-json\/wp\/v2\/posts\/30","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/frpwatertank.co\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/frpwatertank.co\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/frpwatertank.co\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/frpwatertank.co\/index.php\/wp-json\/wp\/v2\/comments?post=30"}],"version-history":[{"count":0,"href":"https:\/\/frpwatertank.co\/index.php\/wp-json\/wp\/v2\/posts\/30\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/frpwatertank.co\/index.php\/wp-json\/wp\/v2\/media\/18"}],"wp:attachment":[{"href":"https:\/\/frpwatertank.co\/index.php\/wp-json\/wp\/v2\/media?parent=30"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/frpwatertank.co\/index.php\/wp-json\/wp\/v2\/categories?post=30"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/frpwatertank.co\/index.php\/wp-json\/wp\/v2\/tags?post=30"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}