Beyond Bottled Water & Storm Floods: 12V Pumping, BS 851188 Flood Defence & Rainwater Filtration

# OFF-GRID ACADEMY FIELD MANUAL 06 ## Beyond Bottled Water & Storm Floods: 12V Pumping, BS 851188 Flood Defence & Biological Filtration ### 1. Why "3 Litres a Day" Is Dangerously Inadequate The UK Cabinet Office advises storing 3 litres of water per person per day for 3 days. While 3 litres covers minimal drinking hydration in cool weather, it leaves **zero water for cooking freeze-dried food, washing wounds, hand hygiene, or flushing toilets**. Within 12–24 hours of a National Grid blackout, urban gravity service reservoirs drain and mains pressure drops to zero. ### 2. UK Roof Catchment Math Even during a dry month, Britain receives regular Atlantic rainfall: ``` Harvestable Litres = Roof Footprint (m²) × Rainfall (mm) × 0.85 (Runoff Coefficient) Example: 75 m² UK semi-detached roof × 15 mm rain shower × 0.85 = 956 Litres ``` A single 1,000-litre food-grade IBC tote (monitored by a **CisternWatch LoRa Ultrasonic Sensor `EOD-WTR-019`**) provides a family of four with **25 litres/day for 40 days**. ### 3. The 3-Tier UK Storm & Flood Defence Protocol (CIRIA C790 & BS 851188-1) During severe UK storms (Desmond, Babet, Henk), 11kV overhead feeders trip just as brooks and culverts overtop—disabling 230V-only sump pumps: - **Tier 1 (Perimeter Exclusion & Sewer Backflow):** Clip **BS 851188-1 Snap-Fit Covers (`OGA-FLD-118`)** onto low-level sub-floor airbricks, slot the **600mm Aluminium Door Dam** into its EPDM side channels, stack **SAP Hydro-Expanding Sacks (`OGA-FLD-117`)**, and push a **110mm BS EN 13564-1 Non-Return Flap Valve** into your manhole outlet so combined sewers cannot erupt through downstairs toilets. - **Tier 2 (1mm Floor Stripping & 35mm Vortex Pumping):** Standard float pumps leave 45mm of water on flat floors (= 2,000L across 50m²). Use a **230V 400W 1mm Flat-Suction "Puddle Sucker" (`OGA-FLD-119`)** to mop thresholds down to 1mm, and a **1100W 35mm Vortex Pump (`OGA-FLD-120`)** for leaf-choked external drains. - **Tier 3 (12V DC Grid-Down Sump & 868MHz LoRa Culvert Early Warning):** Wire a **12V DC 14,000 L/hr Battery Sump System (`OGA-FLD-121`)** directly to a 100Ah LiFePO4 bank (zero inverter idle loss) and mount an **868MHz LoRa Water-Level Siren (`OGA-FLD-122`)** at your upstream culvert trash screen for a 20-minute 85dB bedside warning. ### 4. Multi-Barrier Purification Protocol Never rely on boiling alone for UK urban surface water (canals and rivers contain agricultural nitrates, hydrocarbons, and heavy metals): 1. **Pre-Filtration:** 10-micron sediment spun polypropylene filter. 2. **Primary Membrane:** **AquaSovereign 12V DC Reverse Osmosis (0.0001µm)** (`EOD-WTR-017`) or **StainlessGravity 0.01µm Ultrafiltration** (`EOD-WTR-018`). 3. **Residual Disinfection:** Dose stored filtrate at **2.0 ppm free chlorine** using freshly generated sodium hypochlorite from your **HydroGen USB-C Electrochlorinator (`EOD-WTR-020`)**.