Whole-genome sequencing (WGS) for every UK newborn is hailed as a leap towards lifelong personalised medicine, yet policymakers have scarcely examined the informatics iceberg beneath the initiative: where, and at what cost, will millions of genomes be stored? This perspective contends that the research-era reflex of keeping raw reads and alignments in high-performance ‘hot’ cloud storage is incompatible with NHS budgets and net-zero targets. Drawing on the National Genomic Research Library’s current practice (~80 GB per child), I estimate the UK government’s 10-year rollout would accumulate more than 0.5 exabytes and incur ~£620 million in standard S3 fees—exceeding NICE’s entire core budget over the same period—while driving up data-centre energy demand. By contrast, automatically migrating files to deep-archive tiers 3 months after newborn screening preserves future utility but cuts lifetime storage costs by 91% to about £18 per child and reduces operational power by an order of magnitude; 12–24 hour restore latencies remain clinically acceptable for episodic re-analysis. I argue that newborn sequencing is primarily a logistics challenge rather than a scientific one, and that a national ‘screen-then-archive’ policy, anchored by a retrieval service-level agreement, would safeguard public funds, support workforce expansion and honour NHS carbon commitments while allowing consent-based re-analysis at adolescence or adulthood. Embedding cold storage economics now will prevent the programme from sinking under an exabyte scale liability.